egg tooth

American  

noun

1. a calcareous prominence at the tip of the beak or upper jaw of an embryonic bird or reptile, used to break through the eggshell at hatching.

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egg tooth British  

noun

1. (in embryo birds and reptiles) a temporary tooth or (in birds) projection of the beak used for piercing the eggshell

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egg tooth Scientific  

1. A hard, toothlike projection from the beak of embryonic birds, or from the upper jaw of embryonic reptiles, that is used to cut the egg membrane and shell upon hatching and that later falls off.

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Etymology

Origin of egg tooth

First recorded in 1890–95

Example Sentences

The baby lacked an egg tooth — the hard part of the beak used to crack the shell — and was struggling to get out.

From DOGO News • Sep. 19, 2023

The tiny, weak, featherless creature inside uses its egg tooth, a sharp, horny projection at the end of its beak, to accomplish the task.

From New York Times • Apr. 21, 2011

A sharp egg tooth on the top of its beak pierced the inner membrane, and its nostrils pushed into the pocket of air at the top of the egg.

From "Frightful's Mountain" by Jean Craighead George

After struggling another day, the first chick cut a larger hole and thrust her beak and egg tooth into the air.

From "Frightful's Mountain" by Jean Craighead George

The egg tooth was last seen on a young bird on the sixth day.

From Comparative Breeding Behavior of Ammospiza caudacuta and A. maritima by Woolfenden, Glen E.