Ad′ven‐ti″tious (�), a. [L. adventitius.] 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 district; not fully naturalized; adventive; — applied to foreign plants.
4. (Med.) Acquired, as diseases; accidental.
— Ad′ven‐ti″tious‐ly, adv. — Ad′ven‐ti″tious‐ness, n.