a. 偶然的, 外来的

[医] 偶生的, 偶发的; 异位的

[ adj ]
associated by chance and not an integral part
<adj.all>
poetry is something to which words are the accidental, not by any means the essential formthey had to decide whether his misconduct was adventitious or the result of a flaw in his character

Adventitious \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.