3 letters:
aus

4 letters:
haus, laos, bows, cows, mows, taos, vows, wows

5 letters:
bouse, chaus, couse, douse, dowse, fouse, gauss, graus, hause, hauss, house, houss, klaus, kraus, louse, luaus, mause, mouse, nouse, youse, avows, brows, chows, cow's, cowes, dhows, douze, dow's, houze, how's, howes, howse, howze, mao's, meows, now's, pao's, plows, prows, rao's, scows, thous, touze, wow's, youze

6 letters:
blouse, brouse, clouse, crouse, grouse, hausse, knouse, krauss, krouse, palaus, prouse, rousse, schaus, scouse, shouse, smouse, spouse, straus, trouse, xmouse, allows, arouse, boughs, browse, chouse, clowes, drowse, endows, houghs, howe's, krauze, loughs, prowse, serows, soughs

7 letters:
arbouse, bauhaus, chausse, degauss, espouse, inhouse, jalouse, landaus, milhous, neuhaus, niehaus, palouse, pelouse, rathaus, rehouse, rothaus, sprouse, strause, strauss, strouse, trousse, unhouse, uprouse, zamouse, anthous, carouse, choughs, cloughs, delouse, nothous, ploughs, powwows, schmaus, schnauz

8 letters:
ackhouse, alehouse, althouse, arthouse, backhaus, baghouse, beehouse, berghaus, bighouse, brauhaus, bughouse, burnouse, cathouse, cowhouse, dalhouse, dishouse, doghouse, dormouse, driehaus, durchaus, dyehouse, dykhouse, ecohouse, feldhaus, funhouse, gashouse, gasthaus, ginhouse, grothaus, henhouse, hochhaus, holthaus, hothouse, icehouse, in-house, kamphaus, looshaus, madhouse, milhouse, mughouse, mulhouse, newhouse, nienhaus, nuthouse, outhouse, parkhaus, penhouse, pochouse, pothouse, rathouse, rowhouse, spamhaus, taphouse, teahouse, titmouse, toyhouse, zeughaus, -anthous, aphthous, bandow's, bilbao's, bow-wows, carabaos, disavows, eyebrows, lowbrows, schnauze, spathous, xanthous

9 letters:
abbenhaus, allshouse, almshouse, art-house, babyhouse, backhouse, bakehouse, barklouse, barnhouse, bathhouse, beadhouse, bedehouse, beerhouse, bee house, bellhouse, blockhaus, boathouse, bolthouse, booklouse, brewhouse, brighouse, brockhaus, bunkhouse, cardhouse, chilehaus, chophouse, clubhouse, coalmouse, colemouse, cookhouse, cornhouse, deadhouse, deckhouse, dog house, dollhouse, dosshouse, ex-spouse, farmhouse, firehouse, flophouse, gamehouse, gatehouse, gillhouse, headlouse, hillhouse, hot-house, jailhouse, kilogauss, lamphouse, limehouse, lofthouse, longhouse, mad'house, malthouse, masthouse, megahouse, millhouse, moorhouse, morehouse, neathouse, oncomouse, packhouse, peelhouse, penthouse, pesthouse, pevehouse, pit-house, playhouse, poorhouse, posthouse, pot-house, rearmouse, reermouse, reremouse, roadhouse, rosenhaus, row house, safehouse, sea louse, sea mouse, shophouse, sod house, steinhaus, stenhouse, tollhouse, toolhouse, townhouse, treehouse, treibhaus, warehouse, washhouse, wearhouse, wellhouse, winehouse, wirtshaus, wodehouse, woodhouse, woodlouse, workhouse, -gnathous, acanthous, agnathous, ananthous, disallows, epanthous, highbrows, naphthous, pirithous, snowplows

10 letters:
acid-house, bark-louse, bark louse, bawdyhouse, bird louse, blackhouse, blockhouse, body louse, book louse, brickhouse, brockhouse, card-house, chop-house, clickhouse, clownhouse, coal-house, coal house, courthouse, crab louse, crackhouse, crazyhouse, culvahouse, deck-house, deer mouse, disespouse, doss-house, fieldhouse, fieldmouse, fish louse, flea-louse, full house, glasshouse, greathouse, greenhouse, grindhouse, guardhouse, guesthouse, hash house, head louse, herrenhaus, joss house, lighthouse, meat house, microgauss, microhouse, micromouse, milligauss, moorehouse, moot-house, oast-house, open house, overblouse, pilothouse, pine mouse, powerhouse, pricklouse, pump house, rastamouse, red grouse, rest house, roughhouse, roundhouse, sandgrouse, shrewmouse, smokehouse, spekehouse, stackhouse, stagehouse, statehouse, steakhouse, stillhouse, stonehouse, storehouse, stovehouse, sugarhouse, tittimouse, town house, tree house, trusthouse, watchhouse, waterhouse, wheelhouse, whitehouse, whorehouse, womanhouse, woodgrouse, wood mouse, bismuthous, monanthous, synanthous

11 letters:
adobe house, barrelhouse, bawdy-house, beach house, block-house, chargehouse, churchhouse, clean house, coach house, coffeehouse, courtehouse, crazy house, culverhouse, customhouse, death house, easterhouse, eek-a-mouse, felis chaus, field house, field mouse, funny house, glickenhaus, grape louse, guest-house, hazel mouse, hemminghaus, house mouse, hungryhouse, krankenhaus, lazar house, lenbachhaus, manor house, motherhouse, movie house, onion louse, opera house, plant louse, porterhouse, pubic louse, pygmy mouse, ranch house, rattlemouse, rittenhouse, rottinghaus, rough-house, royal house, ruckelshaus, sage grouse, sand grouse, schoolhouse, shaft louse, solar house, spitalhouse, springhouse, steinkrauss, sugar-house, summerhouse, swishahouse, systemhouse, third house, weigh-house, wendy house, whale louse, white house, whore-house, anacanthous, antipathous, epignathous, middlebrows, nyctanthous, oliganthous, prognathous, rhizanthous, snowploughs

12 letters:
animal house, biting louse, black grouse, cactus mouse, chapterhouse, charterhouse, church mouse, coffee-house, common louse, cotton mouse, custom-house, customshouse, draughthouse, duplex house, eating-house, eating house, fachwerkhaus, flickermouse, flindermouse, flittermouse, flying mouse, fronterhouse, gaming house, garlinghouse, intellimouse, levi-strauss, meadow mouse, meetinghouse, michaelhouse, mickey-mouse, mighty mouse, minnie mouse, modest mouse, niedringhaus, packinghouse, pocket mouse, prison house, public house, stationhouse, summer-house, summer house, tiring-house, vesper mouse, westinghouse, chrysanthous, hapaxanthous, hypognathous, mesognathous, metagnathous, notacanthous, oxyacanthous, paragnathous, six of crows

13 letters:
amy winehouse, auction house, boardinghouse, boultinghouse, cat-and-mouse, chapter-house, charnel-house, chicken louse, clearinghouse, countinghouse, country house, dwellinghouse, dylan sprouse, festspielhaus, gregory house, harvest mouse, holyroodhouse, jumping mouse, kehlsteinhaus, laughinghouse, lodging house, lombard-house, mansion house, meeting-house, meeting house, rooming house, shadows house, splatterhouse, spruce grouse, station house, sucking louse, the owl house, anisognathous, desmognathous, hysteranthous, myriacanthous, orthognathous, proteranthous, saurognathous

14 letters:
boarding-house, boarding house, carriage house, clearing-house, clearing house, detached house, discount house, drinking-house, dwelling house, front-of-house, gambling house, house-to-house, kangaroo mouse, prairie grouse, schauspielhaus, slaughterhouse, sponging-house, sporting house, tenement house, the loud house, tippling-house, treasure-house, treasure house, trugging-house, chaetognathous, schizognathous

15 letters:
apartment house, brokerage house, marsupial mouse, new world mouse, p. g. wodehouse, planetary house, slaughter-house, suki waterhouse, the night house, wholesale house, dromaeognathous, opisthognathous, plec-tognathous

16 letters:
abgeordnetenhaus, chapo trap house, conference house, fraternity house, publishing house

17 letters:
big momma's house, county courthouse, grasshopper mouse, lady of the house, storage warehouse

18 letters:
asian black grouse, bunnings warehouse, silky pocket mouse, white-westinghouse, woman of the house, woolly plant louse

19 letters:
european wood mouse, jumping plant louse, master in the house, plains pocket mouse

20 letters:
carl friedrich gauss, meadow jumping mouse, mexican pocket mouse, monmouth court house, welcome-to-our-house

21 letters:
building supply house, detlev-rohwedder-haus, european black grouse, in the adjacent house

22 letters:
american harvest mouse

30 letters:
battle of monmouth court house

4 letters:
outs

6 letters:
doubts, routes, scouts

7 letters:
lao-tse

11 letters:
thereabouts

16 letters:
brussels sprouts