1. Added extrinsically; not essentially inherent; accidental or causal; additional; supervenient; foreign. To things of great dimensions, if we annex an adventitious idea of terror, they become without comparison greater. Burke. 2. (Nat. Hist.) Out of the proper or usual place; as, adventitious buds or roots. 3. (Bot.) Accidentally or sparingly spontaneous in a country or distric...
