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.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.