A hard white protuberance on the beak or jaw of an embryo bird or reptile that is used for breaking out of the shell and is later lost.
（胎鸟或爬行动物用以刺破卵壳的）卵牙，卵齿
Example sentencesExamples
When more than one chick hatched between nest visits and the hatching order could not be determined by the dampness of the down or the presence of the egg tooth, chicks were assigned the same hatching order.
Snake eggs have a flexible, leathery shell, which the hatchling slashes with its sharp egg tooth before slithering away.
That's an egg tooth that it used to cut its way out of its shell in just the same way as reptiles and birds do.
It's also lacking an egg tooth, but it's got regular teeth in its beak - as well as a long bony tail that make it look rather different from modern birds.
It all started nearly 50 days ago when I poked my egg tooth out of my shell.
Definition of egg tooth in US English:
egg tooth
noun
A hard white protuberance on the beak or jaw of an embryo bird or reptile that is used for breaking out of the shell and is later lost.
（胎鸟或爬行动物用以刺破卵壳的）卵牙，卵齿
Example sentencesExamples
That's an egg tooth that it used to cut its way out of its shell in just the same way as reptiles and birds do.
When more than one chick hatched between nest visits and the hatching order could not be determined by the dampness of the down or the presence of the egg tooth, chicks were assigned the same hatching order.
It all started nearly 50 days ago when I poked my egg tooth out of my shell.
It's also lacking an egg tooth, but it's got regular teeth in its beak - as well as a long bony tail that make it look rather different from modern birds.
Snake eggs have a flexible, leathery shell, which the hatchling slashes with its sharp egg tooth before slithering away.