Adventitious /(ăd`vĕn*tĭsh"ŭs)/

Ad·ven·ti·tious

Adventitious

a.
  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.
  2. Out of the proper or usual place; as, adventitious buds or roots. (Nat. Hist.)
  3. Accidentally or sparingly spontaneous in a country or district; not fully naturalized; adventive; -- applied to foreign plants. (Bot.)
  4. Acquired, as diseases; not hereditary; accidental. (Med.)