What is "adventive"

Adventive \Ad*ven"tive\, a.

1. Accidental.

2. (Bot.) Adventitious.
   --Gray.

Adventive \Ad*ven"tive\, n. A thing or person coming from without; an immigrant. [R.]
--Bacon.

a. 1 accidental 2 adventitious 3 (context biology English) Of a plant that is not native, but was introduced by humans to a place and has since become naturalized. n. A non-native plant that has become naturalized.

adj. not native and not fully established; locally or temporarily naturalized; "an adventive weed"