The shell or external calcareous covering of an egg; often as a type of worthlessness or of fragility.

Scottish. The broad, rounded end of an egg or part of an eggshell. Also figurative. Now rare.

each of the chalazae of a chicken's egg.

In an animal organism. A dark spot visible in a developing bird's egg, representing the germinal point on the yolk. Obsolete.

a reddish pigment occurring in the shells of birds' eggs.