Synonyms and related words :
accessory, accidental, accompanying, additional, ado, adventitious, afloat, afoot, aleatory, auxiliary, behind the scenes, by-the-way, casual, causal, causative, ceremonial, circumstantial, conditional, constitutive, contingent, current, decisive, determinative, doing, effectual, etiological, eventuating, extra, few, formative, going on, happening, in hand, in the wind, incidental, inessential, infrequent, institutive, intermittent, irregular, nonessential, occurring, odd, off, on, on foot, ongoing, originative, out-of-the-way, parenthetical, part-time, particular, passing, periodic, pivotal, prevailing, prevalent, provisional, random, rare, resultant, ritual, scarce, seldom, side, spare, special, sporadic, supplementary, taking place, uncommon, under way, unessential, unfrequent