1. A small knotlike protuberance.
2. Medicine A small, abnormal but usually benign mass of tissue, as on the thyroid gland, in the lung, or under the skin.
3. Botany A small knoblike outgrowth, especially one on the roots of a leguminous plant that contains bacteria that fix nitrogen.
4. Mineralogy A small rounded lump of a mineral or mixture of minerals, usually harder than the surrounding rock or sediment.
[Middle English, from Latin nōdulus, diminutive of nōdus, knot; see ned- in the Appendix of Indo-European roots.]
nodu·lar (nŏjə-lər), nodu·lose′ (-lōs′), nodu·lous (-ləs) adj.
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