noun Botany.
  1. the primary or rudimentary leaf of the embryo of seed plants.
  2. Anatomy. any of several lobules of the placenta.

Origin of cotyledon

1535–45; < Latin: navelwort < Greek kotylēdṓn a plant (probably navelwort), literally, a cuplike hollow, derivative of kotýlē cup
Related formscot·y·le·don·al, cot·y·le·don·ar·y [kot-l-eed-n-er-ee] /ˌkɒt lˈid nˌɛr i/, cot·y·le·don·ous, adjectivenon·cot·y·le·don·al, adjectivenon·cot·y·le·don·ar·y, adjectivenon·cot·y·le·don·ous, adjectivepseu·do·cot·y·le·don·al, adjectivepseu·do·cot·y·le·don·ar·y, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for cotyledon

Historical Examples of cotyledon

British Dictionary definitions for cotyledon


  1. a simple embryonic leaf in seed-bearing plants, which, in some species, forms the first green leaf after germination
  2. a tuft of villi on the mammalian placenta
Derived Formscotyledonous or cotyledonoid, adjectivecotyledonal, adjectivecotyledonary, adjective

Word Origin for cotyledon

C16: from Latin: a plant, navelwort, from Greek kotulēdōn, from kotulē cup, hollow
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for cotyledon

from 1540s, in various sense, from Latin cotyledon "pennywort, navelwort," from Greek kotyledon "cup-shaped cavity," from kotyle "hollow thing, small vessel," also the name of a small liquid measure (nearly a half-pint); of uncertain origin. Botanical sense is 1776, from Linnaeus (1751).

Online Etymology Dictionary, © 2010 Douglas Harper

cotyledon in Medicine


  1. One of the lobules constituting the uterine side of the placenta, consisting mainly of a rounded mass of villi.
  2. A leaf of the embryo of a seed plant, which, upon germination, either remains in the seed or emerges, enlarges, and becomes green; a seed leaf.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

cotyledon in Science


  1. A leaf of the embryo of a seed-bearing plant. Most cotyledons emerge, enlarge, and become green after the seed has germinated. Cotyledons either store food for the growing embryo (as in monocotyledons) or absorb food that has been stored in the endosperm (as in other angiosperms) for eventual distribution to the growing parts of the embryo. Also called seed leaf See more at eudicotyledon monocotyledon.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.