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cot·y·le·don

(kŏt′l-ēdn)

1. Botany A leaf of the embryo of a seed plant, which upon germination either remains in the seed or emerges, enlarges, and becomes green. Also called seed leaf.

2. Anatomy One of the lobules constituting the uterine side of the mammalian placenta, consisting mainly of a rounded mass of villi.

[Latin cotylēdōn, navelwort, from Greek kotulēdōn, from kotulē, hollow object.]

cot′y·ledon·ar′y (-ēdn-ĕr′ē), cot′y·ledon·al (-ēdn-əl), cot′y·ledo·nous (-ēdn-əs) adj.

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cotyledon

bean seed germinating

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:

Indo-European Roots

Semitic Roots

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.

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