1. (a.) Added extrinsically; not essentially inherent; accidental or causal; additional; supervenient; foreign.

2. (a.) Out of the proper or usual place; as, adventitious buds or roots.

3. (a.) Accidentally or sparingly spontaneous in a country or district; not fully naturalized; adventive; -- applied to foreign plants.

4. (a.) Acquired, as diseases; accidental.

accessory accidental additional adscititious aleatory appurtenant ascititious auxiliary casual causeless chance chancy circumstantial collateral conditional contingent destinal dicey extra fatal fatidic fluky fortuitous iffy incidental indeterminate inessential nonessential occasional provisional risky secondary subsidiary superadded superfluous supervenient supplemental supplementary uncaused undetermined unessential unexpected unforeseeable unforeseen unlooked-for unpredictable