embryo

1 of 2

noun

em·​bryo ˈem-brē-ˌō 

plural embryos

1

a

: an animal in the early stages of growth and differentiation that are characterized by cleavage, the laying down of fundamental tissues, and the formation of primitive organs and organ systems

especially : the developing human individual from the time of implantation to the end of the eighth week after conception

b

archaic : a vertebrate at any stage of development prior to birth or hatching

2

: the young sporophyte of a seed plant usually comprising a rudimentary plant with plumule, radicle, and cotyledons

3

a

: something as yet undeveloped

b

: a beginning or undeveloped state of something

… productions seen in embryo during their out-of-town tryout period …

—Henry Hewes

embryo-

2 of 2

combining form

: embryo

embryogeny

Examples of embryo in a Sentence

Recent Examples on the Web

Noun

Last year the Women’s Tennis Association (WTA) began offering rankings protection if players decide to undergo an egg or embryo freezing procedure. — Adam Kovac, Scientific American, 18 Aug. 2026

There are still so many steps that egg would have to make it through later in the IVF process (thawing, fertilization, embryo development and more) and eggs can be lost at each step. — Cara Lynn Shultz, PEOPLE, 18 Aug. 2026

The couple who hired her and whose embryo was used named her Rumi. — Arthur L. Caplan, STAT, 18 Aug. 2026

Project 2025 laid bare plans to declare fetuses and embryos as people with legal rights. — Brittany Fonteno, Time, 17 Aug. 2026

Word History

Etymology

Noun

Middle English embrioun "embryo, fetus," borrowed from Medieval Latin embrion-, embrio, embryo, borrowed from Greek émbryon "newborn creature (in reference to a lamb), young, embryo or fetus," from em- em- + -bryon, derivative of bry-, stem of brýein "to swell with an abundance of growth, bloom, abound," of obscure origin

Note: In Medieval Latin the Greek neuter noun émbryon was reanalyzed as the base of Latin nasal stems (such as sermōn-, sermō "speech"), resulting in the nominative singular form embryo, which was borrowed into English. The stem embryon- was employed in New Latin derivatives, the sources of embryonal and embryonic. Compare bryo-.

Combining form

Late Latin, from Greek, from embryon

First Known Use

Noun

1548, in the meaning defined at sense 1b

Phrases Containing embryo

• embryo sac
• embryo transfer
• in embryo

Rhymes for embryo

• acknow
• aglow
• ago
• airglow
• aloe
• altho
• although
• ammo
• backflow
• backhoe
• banjo
• barbeau

Kids Definition

embryo

noun

em·​bryo ˈem-brē-ˌō 

plural embryos

1

: an animal in the early stages of development that are marked by cleavage, the laying down of the basic tissues, and the formation of primitive organs and organ systems compare fetus

2

: a tiny young plant within a seed

3

: a beginning or undeveloped stage

—used especially in the phrase in embryo

Medical Definition

embryo

noun

em·​bryo ˈem-brē-ˌō 

plural embryos

1

archaic : a vertebrate at any stage of development prior to birth or hatching

2

: an animal in the early stages of growth and differentiation that are characterized by cleavage, the laying down of fundamental tissues, and the formation of primitive organs and organ systems

especially : the developing human individual from the time of implantation to the end of the eighth week after conception compare fetus