early 15c., "having steps or ridges," from Medieval Latin gradualis, from Latin gradus "a step; a step climbed; a step toward something, a degree of something rising by stages" (from PIE root *ghredh- "to walk, go"). Meaning "arranged by degrees" is from 1540s; that of "taking place by degrees" is from 1690s.
word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.