Find over 25,000 psychological definitions


n. the outermost of the primary germ layers of a developing embryo. Structures derived from ectoderm include skin and nails, hair, glands, mucous membranes, the nervous system, and external sense organs (e.g., ears, eyes). —ectodermal adj.

Browse dictionary by letter

a b c d e f g h i j k l m n o p q r s t u v w x y z

Psychology term of the day

March 3rd 2024

closed-class words

closed-class words

in a language, a category of words that does not readily admit new members, consisting mainly of words that serve key grammatical functions, such as pronouns, prepositions, and determiners (see function word). Compare open-class words.