What does "adventitious" mean?

Adventitious: (Nat. Hist.) Out of the proper or usual place; as, adventitious buds or roots.

Additional senses

  1. 2.(Bot.) Accidentally or sparingly spontaneous in a country or district; not fully naturalized; adventive; -- applied to foreign plants.
  2. 3.(Med.) Acquired, as diseases; accidental. -- Ad`ven*ti"tious*ly, adv. -- Ad`ven*ti"tious*ness, n.

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