adventitious

From Latin adventicius (“foreign”), from adveniō (“arrive”).

• IPA^(key): /ˌæd.vənˈtɪʃ.əs/, /ˌæd.vɛnˈtɪʃ.əs/
• (Northern California)

  (file)

adventitious (comparative more adventitious, superlative most adventitious)

1. From an external source; not innate or inherent, foreign.
2. Accidental, additional, appearing casually.
   • 2002, Colin Jones, The Great Nation, Penguin 2003, p. 30:

     The adventitious disappearance of those nearer the throne than the duke had, moreover, set tongues awagging.

3. (genetics, medicine) Not congenital; acquired.
4. (biology) Developing in an unusual place or from an unusual source.
   • 1985, R. M. T. Dahlgren, H. T. Clifford, & P. F. Yeo, The Families of the Monocotyledons, page 101

     The Velloziaceae have evolved a woody stem which is covered with a layer of adventitious roots mingled with the fibres of the old leaf sheaths;

• (from an external source): extrinsic
• (accidental, additional): accidental, spontaneous, sporadic
• (not congenital): acquired

• adventitiously
• adventitiousness

• advent
• adventitial
• adventition
• adventive
• adventively