-ast, one who (does): elegiast, enthusiast, gymnast, symposiast.
-ic (-ics), an art, science: logic, music, phthisic (asthma), physic (science of medicine), ethics, physics, politics, statics, tactics.
-isk, diminutive: asterisk (= little star), obelisk (little spit or pillar).
-ism, act of, result, state, doctrine: atheism, baptism, criticism, euphemism, socialism, schism, syllogism, Anglicanism, stoicism.
-ist, denotes practice, occupation: apologist, chemist, copyist, elegist, eulogist, Hebraist, organist.
-ma, -m, result produced: asthma, diorama, dogma, drama, apothegm, theorem.
-sis, act of, result: analysis, emphasis, genesis, periphrasis, synthesis.
-sy, like -sis: apostasy, epilepsy, hypocrisy, idiosyncrasy, palsy (= paraly-sis), poesy.
-t, -te, one who (does or is): apostate, comet (= long-haired), planet (= wanderer), poet (= maker).