Adventitious, a.
Etymology: [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.)
3 more senses
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.
Shades of meaning
Fernald lists adventitious only as an antonym, under primeval.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given