Adventitious (adjective)

1. Happening or occurring by chance or unexpectedly.
2. Not arising from or inherent in a particular situation, substance or organism.

Origin:

Derived from the latin word adventicius, meaning 'coming from without'.

Examples:

1. The adventitious discovery of oil in the area brought sudden prosperity.
2. The adventitious root system is capable of absorbing water and nutrients.
3. An adventitious meeting led to a lifelong friendship.
4. Adventitious sounds are unintentional sounds in audio recording.
5. The adventitious spores were removed from the plant tissue.