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.
Accidentally or sparingly spontaneous in a country or district; not fully naturalized; adventive; — applied to foreign plants.
Acquired, as diseases; accidental.