adventitious

Etymology

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

adj

1. From an external source; not innate or inherent, foreign.
2. Accidental, additional, appearing casually.
   The discovery of the art of making pottery was probably in all cases adventitious, the clay being first used for some other purpose. 1895, Alfred C. Haddon, Evolution in Art, pages 101–102
   The adventitious disappearance of those nearer the throne than the duke had, moreover, set tongues awagging. 2002, Colin Jones, The Great Nation, Penguin, published 2003, page 30
3. (genetics, medicine) Not congenital; acquired.
4. (biology) Developing in an unusual place or from an unusual source.
   Coordinate term: ectopic
   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; 1985, R. M. T. Dahlgren, H. T. Clifford, P. F. Yeo, The Families of the Monocotyledons, page 101