Definition of "adventitious" []

• Not inherent but added extrinsically. See Synonyms at accidental. (adjective)
• Biology Of or belonging to a structure that develops in an unusual place: adventitious roots. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Cuttings are plant pieces, usually stems or branches, capable of growing new roots, called adventitious roots."
• "Leaf-buds occasionally arise from the roots, when they are called adventitious; this occurs in many fruit trees, poplars, elms and others."
• "But as it was occasionally inexpedient to carry about measuring-chains a boy would do well to know the precise length of his own foot-pace, so that when he was deprived of what Hurree Chunder called adventitious aids 'he might still tread his distances."