ectoderm

noun

ec·​to·​derm ˈek-tə-ˌdərm 

1

a

: the outermost of the three primary germ layers of an embryo that is the source of various tissues and structures (such as the epidermis, the nervous system, and the eyes and ears)

b

: a tissue (such as neural tissue) derived from this germ layer

2

: the outer layer of cells of a diploblastic animal (such as a jellyfish or sponge)

ectodermal

ˌek-tə-ˈdər-məl 

adjective

Examples of ectoderm in a Sentence

Recent Examples on the Web

Then, in the developing embryo, cells form three primary layers — ectoderm, mesoderm and endoderm — which, over time, become skin, neurons, heart, gut, and so on. —Viviane Callier, Quanta Magazine, 21 Mar. 2025

There are a number of genetic disorders that can affect the ectoderm; this approach will not work across the board, experts say. —Michael Nedelman, CNN, 18 May 2018

The outermost layer, the ectoderm, contributes to a number of structures including the skin, teeth, hair and sweat glands. —Michael Nedelman, CNN, 18 May 2018

Word History

Etymology

International Scientific Vocabulary

First Known Use

1859, in the meaning defined at sense 2

Rhymes for ectoderm

• disaffirm
• endoderm
• endosperm
• interfirm
• isotherm
• mesoderm
• periderm
• reaffirm
• affirm
• bookworm
• confirm
• cutworm

Kids Definition

ectoderm

noun

ec·​to·​derm ˈek-tə-ˌdərm 

1

: the outer layer of cells of a two-layered animal (as a jellyfish)

2

: the outermost of the three basic layers of an embryo from which skin, nerves, and certain other structures develop

ectodermal

ˌek-tə-ˈdər-məl 

adjective

Medical Definition

ectoderm

noun

ec·​to·​derm ˈek-tə-ˌdərm 

1

: the outermost of the three primary germ layers of an embryo

2

: a tissue (as neural tissue) derived from ectoderm

ectodermal

ˌek-tə-ˈdər-məl 

adjective