nodule

nodule

1. any of the knoblike outgrowths on the roots of clover and many other legumes: contain bacteria involved in nitrogen fixation

2. Anatomy any small node or knoblike protuberance

3. a small rounded lump of rock or mineral substance, esp in a matrix of different rock material

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

nodule

[′näj·ül]

(anatomy)

A small node.

A small aggregation of cells.

(botany)

A bulbous enlargement found on roots of legumes and certain other plants, whose formation is stimulated by symbiotic, nitrogen-fixing bacteria that colonize the roots.

(geology)

A small, hard mass or lump of a mineral or mineral aggregate characterized by a contrasting composition from and a greater hardness than the surrounding sediment or rock matrix in which it is embedded.

(medicine)

A primary skin lesion, seen as a circumscribed solid elevation.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.