1 letter:
i, y

2 letters:
ai, bi, by, cy, fi, hi, hy, i., ly, my, pi, sy, ty, vi, vy, y.

3 letters:
aye, bae, bly, buy, bye, cai, chi, cry, csi, dai, die, dry, dui, dwi, dye, eye, fae, fbi, fly, fry, fye, fyi, gae, guy, hye, jai, kai, lai, lie, lti, lye, mai, mei, nye, pae, phi, phy, pie, ply, pri, pry, psi, pty, pye, rye, sai, shy, sky, sly, spy, sty, tai, thy, tie, tri, try, tye, vie, wai, why, wry, wye

4 letters:
akai, alai, ally, awry, bely, blye, brye, chae, chai, crye, cspi, defy, deny, drye, flye, frei, frye, heye, high, if i, imai, isty, iwai, jedi, july, keye, kwai, ngai, nigh, rely, shai, sigh, skye, slye, spry, thai, trie, tsai, wifi, wrye

5 letters:
99.9%, ahigh, aimai, alibi, altai, and i, anigh, apply, assai, attai, bahai, baiae, balai, barye, belie, bligh, bohai, but i, copii, cotai, dacry, dahae, dalai, danai, debye, deci-, decry, defly, deify, domai, douai, do by, dreye, dubai, eccai, edguy, edify, eisai, eleni, essai, flyby, go-by, gofai, go by, gusli, hawai, hegai, heigh, hi-fi, i-fly, iclei, imply, imsai, ineye, in my, ittai, ixtli, janai, jubae, kadai, kalaj, kanai, kauai, kawhi, khmer, kitai, kitaj, kukai, kunai, kutai, lanai, li-fi, ligni, lo-fi, madai, malai, mapai, mcfly, mihai, mogai, mohai, murai, naify, nanai, oculi, oxfly, pari-, pci-e, pci-x, pohai, powai, pupae, rabbi, radii, raiae, rebuy, reify, reply, retie, retry, rifai, roguy, rubai, saifi, salai, sanai, satai, scbwi, schei, scifi, selye, serye, shuai, sinai, sligh, stoae, strei, stryi, styli, tapai, thigh, togae, tokai, tokaj, tupai, unify, untie, uptie, vari-, vinai, wadai, warye, wi-fi, wifie, yobai, yokai

6 letters:
abisai, adonai, aerify, agapae, akamai, alkali, alumni, ambuli, amebae, amitai, annuli, arrhae, aurify, baligh, bandai, barbae, barfly, barkai, basify, bawtry, beihai, bhilai, bidpai, bigeye, blagaj, bobfly, boktai, bonify, bonsai, boohai, botfly, brunei, bugeye, cabify, calci-, calefy, cestuy, chequy, chimay, chugai, citify, cliquy, codify, comply, contai, credai, cumuli, dayfly, deafly, descry, digiti, dmitry, domify, durbuy, energi, entify, eun-bi, euouae, eye-fi, finify, fly-by, fly by, forbye, foreby, forlye, fumify, g.u.y., gadfly, gaikai, galibi, gemini, get by, gilgai, gimhae, glebae, goodby, gorfly, graiae, gunbai, haikai, hamuli, hanafi, haveli, hentai, hercai, hereby, hermai, hiddai, humify, hushai, ignify, imrigh, incubi, itsfwi, jahdai, kaalai, kaikai, kansai, karzai, katmai, keitai, kichai, kookai, korkai, kowhai, labefy, ladify, lahaie, laogai, laowai, lapwai, lay-by, lcp fy, leafly, leelai, lehigh, lenify, licify, liga i, ligni-, limuli, lipsky, loculi, low-fi, machai, madefy, maglaj, magpie, mandai, mannai, maotai, mary i, mayfly, minify, minimi, misgye, mistry, modify, mogwai, mumbai, mumtaj, munify, nanhai, nankai, nazify, nearby, netify, nidify, nilgai, no-fly, notify, nuchae, nuclei, nugify, nuncii, nurzai, occupy, oishii, omnify, openai, osakai, ossify, outcry, outfly, ox-eye, pacify, paepae, papyri, patkai, pigsty, pillai, pisci-, plaguy, popeye, populi, potpie, purify, rabais, ramify, rarify, ratify, reguli, reneye, ribeye, rinnai, rinzai, ripply, rubefy, rubify, run by, ruswai, saifai, salify, salpae, sandai, sarraj, saufly, sawfly, sawtry, scheie, schlei, schrei, sci-fi, scopae, seelye, sendai, sentai, sextry, shagai, shinai, shumai, sikhye, sinify, sit by, snes9x, sonify, styli-, sundai, supply, survie, switaj, tabefy, talmai, tanguy, taotai, tendai, tenkai, that i, tineye, tonguy, tonify, tubuai, tubuli, typify, uglify, varify, verify, vettai, vilify, vinify, vivify, webeye, webify, weihai, wen-li, what i, wikify, xuemei, xunlei, yantai, yentai, zabbai, zaikai, zentai, zhuhai, zip by

7 letters:
17-sai., abilify, abishai, acetify, acidify, air-dry, aloofly, alveoli, amashai, amittai, amoebae, amplify, anglify, apple i, areolae, asmodai, assegai, athenai, autodie, avowtry, bacchii, bad guy, balmify, beatify, bee fly, bergylt, blow-by, blowdry, blowfly, blutmai, bow tie, brachii, brassai, brutify, buckeye, bullfly, bye-bye, calcify, calculi, candify, carnify, centri-, certify, chembai, chennai, chubais, chun-li, chylify, chymify, clarify, cockeye, come by, conchae, cornify, cretify, cripply, crucify, cup tie, cut-eye, damnify, dandeli, dandify, deerfly, denbigh, densify, densiti, dignify, dongmei, doomguy, dorrfly, drop by, dry fly, dulcify, duncify, eagleye, falsify, fancify, far cry, fast.ai, firefly, fishfly, fishify, foolify, fortify, fritfly, frogeye, fuerdai, gallfly, galvani, gamefly, glorify, glowfly, good-by, goodbye, gratify, grayfly, gut-tie, haganai, hang-by, hard-fi, hawkeye, hebbuli, hokusai, hornify, horrify, hwachae, iconify, infobae, inotify, iyarkai, japchae, jellify, jeremih, jijabai, jollify, jundiai, justify, kahawai, kakazai, kakifly, kam-tai, kasugai, kokusai, kthxbye, kutenai, lac dye, let fly, lignify, liquefy, liquify, lithify, live by, loralai, lorelei, louiguy, lullaby, magnify, mai-mai, mao-tai, mattify, may-fly, mercify, metrify, micrify, mollify, molokai, monnaie, morotai, mortify, mummify, mundify, mystify, nearbuy, neatify, necktie, neidigh, netlify, nicolae, nigrify, nikolai, nikolaj, nitrify, nomikai, norigae, nullify, nutrify, nylghai, off-dry, onyalai, opacify, orakzai, osmanli, overbuy, overfly, pass by, pe-tsai, petrify, pinkeye, pinkify, planify, pop-fly, pop fly, pulpify, putrify, pyrenae, qinghai, qualify, rainfly, rectify, red-eye, red tai, reedify, reunify, rockeye, run dry, russify, saattai, salsify, samurai, sandfly, satagaj, satisfy, saw-fly, scarify, scorify, scorpii, scrapie, segovii, semidry, sensify, sesqui-, shaddai, shadfly, shalmai, shammai, shan-si, shehnai, shintai, shoefly, shoofly, shopify, signify, sitonai, skyhigh, slip by, sockeye, songhai, soulfly, specify, spotify, standby, stimuli, storify, stupify, suavify, succubi, tarabai, tawkify, termini, terrify, testify, thereby, thurify, tiantai, tie dye, tipsify, toonzai, torpify, torrify, tournai, turk-is, undeify, underly, uruguay, ushguli, vaaimai, valimai, vat dye, venghai, ventri-, verbify, versify, vitrify, vowi-fi, walleye, war cry, wet fly, whereby, wildfly, wiseguy, xingtai, yamibuy, yuppify, zincify, zombify

8 letters:
0.999..., 2c-b-fly, abide by, acanthae, ace-high, acephali, actiniae, adimurai, advowtry, againbuy, alacrify, alderfly, alkalify, ammonify, angelify, antinomy, ard-righ, articuli, ashmedai, battosai, beautify, bed-stuy, bhatiali, bidorbuy, blackfly, bleareye, blow-dry, blow-fly, blow fly, blue-eye, blue sky, bogotify, bola tie, bone-dry, bone dry, bulk-buy, c. p. i., capacify, casetify, catchfly, cats-eye, caveolae, chagatai, chelubai, chigetai, chinghai, chlorobi, classify, close-by, cranefly, daintify, damp-dry, daphnaie, dead-eye, denazify, detoxify, devathai, disapply, disdeify, disedify, disunify, divinify, drip-dry, drive-by, e-hentai, e-verify, emulsify, esterify, eternify, etherify, evil eye, exist by, f. b. i., fairyfly, fall guy, fast dye, firstcry, fish-eye, fish-fly, fish fry, flocculi, flydubai, fly high, foveolae, free guy, fructify, fruitfly, funiculi, gentrify, glide by, good-bye, good guy, gramarye, grandayy, greeneye, greenfly, haeremai, hair dye, hand dye, hawk-eye, helvetii, heydeguy, horn fly, horsefly, housefly, hoverfly, humanify, humidify, hushabye, hysminai, identify, igoodbye, imaqtpie, in reply, jai alai, jambinai, jb hi-fi, kaientai, kalsubai, karachai, karstify, kiang-si, kiheitai, kiln-dry, kino-eye, kkangpae, kodo-kai, kootenai, kudo-kai, kure-nai, lahoriye, lapidify, lapithae, leopardi, lienculi, lullabye, m. c. i., m. r. i., malayali, meat pie, mebunnai, meningi-, mid-july, misapply, mobileye, molkerei, moon-eye, mordecai, multiply, musaceae, nannygai, nattamai, nickolay, nightcry, nobilify, opsonify, overhigh, p. r. i., pakhavaj, pale-dry, paleolae, pearleye, pediculi, pemulwuy, peranmai, pinguefy, pork pie, pothigai, prettify, quantify, remodify, repacify, repurify, resinify, resupply, reticuli, revivify, rigidify, saenchai, salomtry, sanandaj, sand fly, sanguify, saponify, sartorii, sassabye, selachii, semi-dry, sensori-, shanghai, shimshai, shoo fly, shut-eye, signifie, silicify, simplify, siruthai, sky-high, sleepify, slide by, snakefly, solidify, spin-dry, stand-by, stand by, stellify, stick by, stiltify, stir fry, stonefly, stratify, stultify, superfly, swing-by, t. c. i., tent-fly, tentifly, test-fly, test fly, thoranai, timethai, trendify, tsinghai, underbuy, undercry, underlie, unnotify, uralkali, uruk-hai, utriculi, wakkanai, wall-eye, wannacry, wellnigh, whisk by, whitefly, wild rye, wise guy, yusufzai, zauberei

9 letters:
abscissae, adsignify, al-hallaj, alder fly, amazon.ae, anandibai, anglicify, antalkali, anthousai, apple pie, aranmanai, barreleye, battlecry, battousai, beddy-bye, bindi-eye, birds-eye, black eye, black fly, black tai, black tie, bulls-eye, butterfly, by-and-by, by and by, caddisfly, cat's eye, cauliculi, celestify, chatichai, chiangmai, chiengmai, chondrify, codentify, colliculi, commodify, corporify, countrify, crane-fly, crane fly, cross-eye, damselfly, danchigai, deacidify, decalcify, decertify, demassify, demideify, demulsify, demystify, denitrify, devitrify, dezincify, diabolify, diversify, dobsonfly, dojin-kai, dragonfly, dziggetai, electrify, endamnify, entamebae, exemplify, expensify, ezhumalai, fasciculi, fasciolae, fe-licify, fecundify, felipe vi, flesh-fly, flesh fly, frenchify, fruit fly, george vi, glass eye, globaleye, goldeneye, havasupai, historify, homunculi, horse-fly, horse fly, house-fly, indemnify, indignify, intensify, irgendwie, jaddanbai, jaggubhai, kempeitai, kitschify, knee-high, kuringgai, life time, limicolae, loasaceae, louse fly, magic eye, malignify, mangawhai, marie-mai, mercurify, mince pie, mononokai, mordechai, mottainai, muay thai, naked-eye, nanawatai, nhulunbuy, papaoutai, passer-by, pecan pie, personify, pizza pie, preachify, preoccupy, pretypify, primitiae, pronuclei, rancidify, ranunculi, recarnify, refortify, requalify, romajikai, rough-dry, rukhmabai, sacchari-, scrape by, screw eye, semideify, sengottai, shang-hai, shinsegae, shinsekai, shortugai, sirumalai, slant-eye, small fry, smoke-dry, solemnify, soyarabai, speechify, spiegelei, splenculi, spongefly, spray-dry, squeak by, stewartry, stink fly, stone fly, sukhothai, syllabify, syracusae, tabatabai, taeniolae, takanakuy, tatenokai, third eye, tiger-eye, timenoguy, tirumurai, tough guy, travel by, triunguli, tubicolae, type-high, ultrahigh, unglorify, unqualify, urbicolae, uriankhai, visaranai, well-nigh, white-eye, white tai, white tie, world2fly, yanktonai, yongin-si

10 letters:
agalactiae, altocumuli, annaamalai, battle cry, biomagnify, bird's eye, bull's eye, butter-fly, by the bye, c.r.a.z.y., caddicefly, caddis-fly, canaliculi, chalcidfly, compactify, complexify, connectify, consignify, declassify, democratie, disacidify, disglorify, disqualify, dissatisfy, dobson fly, double dye, dracunculi, eau de vie, entamoebae, euselachii, ferret-eye, freeze-dry, french fry, french rye, goggle-eye, golden-eye, gravimetry, hannah fry, hay-on-wye, hbomberguy, heddle-eye, hyperbolae, jewish rye, kidney pie, lanternfly, m.i.a.m.i., massagetae, mayacaceae, medininkai, medium-dry, mind's eye, myxamoebae, naumachiae, on-the-fly, on the sly, oversupply, passers-by, pineal eye, prequalify, presignify, public eye, rajapattai, reclassify, reidentify, robber fly, rock-a-bye, saccharify, sarazanmai, shabbethai, shibaozhai, shutterfly, silver-eye, simple eye, squash pie, squeeze by, squint-eye, stander-by, string tie, suitsupply, terricolae, thigh-high, thirumalai, thomsonfly, tinder-dry, tongue tie, tsetse fly, tubulariae, tumble-dry, u.n.i.t.y., unclassify, versailles, waist-high, zaporozhye

11 letters:
ammishaddai, aniline dye, ascidiaceae, bell magpie, breast-high, caddice-fly, cirrocumuli, crossed eye, cut-and-dry, ephedraceae, etymologiae, foresignify, harvest fly, hessian fly, hue and cry, impulse-buy, inagawa-kai, italian rye, jhalkaribai, junior high, khasekhemwy, lantern-fly, lantern fly, macronuclei, manimekalai, matsuba-kai, micronuclei, misclassify, misidentify, mount sinai, musicmagpie, myxophyceae, overmagnify, overqualify, paludicolae, private-eye, private eye, pudhupettai, pumpkin pie, red buckeye, rhubarb pie, ross-on-wye, saururaceae, scorpionfly, senior high, shoofly pie, smilacaceae, spanish fly, stephen fry, styracaceae, subclassify, symbranchii, telotrochae, terrestrify, tones and i, undersupply, vinegar fly, weather eye, windsor tie, zhongnanhai

12 letters:
bibliobibuli, blue walleye, bourgeoisify, caravanserai, central thai, chuttalabbai, compound eye, cupressaceae, cyanophyceae, davalliaceae, derek jacobi, discocephali, dissyllabify, divisible by, dominated by, dragon's eye, druskininkai, echcharikkai, electric eye, f.r.i.d.a.y., geglossaceae, give the eye, golden kamuy, goodspaceguy, hariphunchai, hellogoodbye, hook and eye, horse botfly, hotel mumbai, human botfly, hydrophiinae, isle of skye, lee chih-kai, mackerel sky, money supply, nedunchaalai, northern spy, no man's sky, ohio buckeye, oleandraceae, overmultiply, oversimplify, papaveraceae, phaeophyceae, railroad tie, rallying cry, raspberry pi, rhodophyceae, scorpion-fly, sheep botfly, sheep gadfly, southern tai, sowkarpettai, stratocumuli, streamer fly, subdiversify, super sentai, t.a.h.i.t.i., tintinnabuli, tlaltecuhtli, transmogrify, water supply, wong kar-wai, xiuhtecuhtli, yacatecuhtli, yoon eun-hye

13 letters:
adl-tabatabai, blood red sky, blueberry pie, captain bligh, chrysophyceae, devil may cry, dwarf buckeye, geoglossaceae, give it a try, hotepsekhemwy, interstratify, lophobranchii, lugal-zage-si, parangipettai, park geun-hye, park shin-hye, portulacaceae, qaid-e-tanhai, sacrifice fly, schizophyceae, shoulder-high, subak-hwachae, sumiyoshi-kai, sundar pichai, sweet buckeye, tesla model y, william bligh

14 letters:
13 reasons why, cross-multiply, diatomophyceae, dil chahta hai, elasmobranchii, euglenophyceae, fourth of july, hempen necktie, indivisible by, in a pig's eye, james vi and i, makoto shinkai, menispermaceae, old school tie, red bird's eye, scyphobranchii, see eye to eye, shepherd's pie, tiruvannamalai, uitzilopochtli

15 letters:
aizukotetsu-kai, american magpie, blink of an eye, bromo-dragonfly, canada wild rye, comma butterfly, european magpie, fluorescent dye, huitzilopochtli, kawakami gensai, mictlantecuhtli, ncaa division i, ophioglossaceae, piltzintecuhtli

16 letters:
basavaraj bommai, boston cream pie, curse of the fly, kuttrapathirikai, lepidodendraceae, malala yousafzai, pharyngobranchii, sulfur butterfly, thermogravimetry, the midnight sky, turn a blind eye, zannichelliaceae

17 letters:
australian magpie, cabbage butterfly, emperor butterfly, give the glad eye, monarch butterfly, peacock butterfly, sulphur butterfly

18 letters:
kuch kuch hota hai, milkweed butterfly, mumbai-pune-mumbai

19 letters:
larry the cable guy, namma veettu pillai, times-or-divided-by, tony leung chiu-wai, to pimp a butterfly

20 letters:
steak and kidney pie

21 letters:
allies of world war i, one night in miami..., umineko when they cry

22 letters:
digimon adventure tri.

23 letters:
higurashi when they cry, mediterranean fruit fly, music to be murdered by

24 letters:
mourning cloak butterfly

26 letters:
southern cabbage butterfly, yeh rishta kya kehlata hai

28 letters:
fast times at ridgemont high, northrop grumman e-2 hawkeye, the bridge on the river kwai