Definition of cotyledon in English:



  • 1Botany
    An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.

    • ‘They are present on the stems, leaves, cotyledons, rachises, pedicles, bracts and calyces.’
    • ‘The cotyledons are the ‘seed leaves’ produced by the embryo.’
    • ‘However, protein biosynthesis in the axis organs and cotyledons of dicotyledonous seeds commences much earlier.’
    • ‘Mutants of this class display shortened hypocotyls and small cotyledons after irradiation of seed.’
    • ‘The layer between seed coat and cotyledon probably includes the wall of the embryo sac.’
  • 2A succulent plant of the stonecrop family, some kinds of which are grown as ornamentals.


Mid 16th century (denoting a patch of villi on the placenta of mammals): from Latin, navelwort (which has cup-shaped leaves), from Greek kotulēdōn cup-shaped cavity, from kotulē cup.