2 syllables:
-blastic, -nastic, -plastic, blastic, clastic, drastic, mastek, mastic, mastick, nastic, plastic, plastik, spastic, tastic

3 syllables:
aclastic, aplastic, bombastic, chalastic, chiastic, dicastic, dichastic, doxastic, dynastic, dysplastic, elastic, emplastic, entastic, ergastic, euplastic, fantastic, fantastik, gelastic, gymnastic, gymnastik, jelastic, lantastic, monastic, orgastic, peirastic, pepastic, phantastic, poptastic, proplastic, sarcastic, scholastic, silastic, stochastic, symplastic, synclastic

4 syllables:
alloplastic, amphiblastic, anaclastic, anaplastic, animastic, antiblastic, anticlastic, antiphrastic, antiplastic, antispastic, astochastic, autoclastic, autoplastic, bioclastic, bioplastic, bitumastic, cacoplastic, cataclastic, cataplastic, ceroplastic, chiliastic, chloroplastic, cosmoplastic, cryptoclastic, cyberspastic, cytoclastic, cytoplastic, desmoplastic, deutoplastic, diploblastic, discoblastic, docimastic, dokimastic, ectoplastic, endoblastic, entoplastic, epiblastic, epinastic, epipastic, epispastic, esemplastic, fibroblastic, fibroplastic, gum elastic, gymnoblastic, haemoplastic, hesychastic, holoblastic, holophrastic, homoblastic, homoplastic, hudibrastic, hyperplastic, hypoblastic, hyponastic, hypoplastic, inelastic, lymphoblastic, meloplastic, meroblastic, mesoblastic, metaphrastic, metaplastic, monoplastic, myoblastic, neoblastic, neophrastic, neoplastic, nonelastic, nyctinastic, onomastic, orgiastic, orthoclastic, paederastic, parablastic, paracmastic, paraphrastic, paraplastic, pederastic, periphrastic, phelloplastic, phonetastic, pleonastic, polyplastic, pornerastic, predynastic, protoplastic, pyroclastic, rhinoplastic, scholiastic, superplastic, thermoplastic, thromboplastic, triploblastic, trophoblastic, unelastic, unsarcastic, vasospastic, xyloplastic, zooplastic, zymoplastic

5 syllables:
achondroplastic, aeroelastic, ameloblastic, amino plastic, amyloplastic, angiospastic, antigalastic, antiorgastic, antonomastic, blepharoplastic, dermatoplastic, ecclesiastic, embryoplastic, encomiastic, enthusiastic, epicerastic, erythroblastic, erythroclastic, fibrinoplastic, galvanoplastic, haematoplastic, heteroblastic, heteroplastic, homoscedastic, iconoclastic, idioblastic, interscholastic, keratoplastic, megaloblastic, melanoblastic, myeloblastic, neo-scholastic, nonneoplastic, odontoblastic, organoplastic, osteoblastic, osteoclastic, osteoplastic, pancratiastic, paronomastic, phenolic plastic, plagioclastic, porphyroblastic, stomatoplastic, visco-elastic, viscoelastic, volcaniclastic

6 syllables:
antineoplastic, autoschediastic, fluorocarbon plastic, heteroskedastic, paraneoplastic, trip the light fantastic, unenthusiastic

7 syllables:
overenthusiastic

2 syllables:
asdic, aspic