A yolk is the inner, yellow part of an egg. If you order eggs "sunny side up," those "suns" are the egg yolks.

When a bird lays an egg that's fertilized and begins to grow into a baby bird, the yolk is the substance that nourishes the bird embryo. The eggs we eat have yolks too, but since they are unfertilized, these protein-rich yolks can be beaten into omelettes or mixed into cake batter. The Old English root of yolk, geolca, literally means "the yellow part."

Definitions of yolk

n nutritive material of an ovum stored for the nutrition of an embryo (especially the yellow mass of a bird or reptile egg)

Type of:
food, nutrient
any substance that can be metabolized by an animal to give energy and build tissue

n the yellow spherical part of an egg that is surrounded by the albumen

egg yolk
Type of:
fixings, ingredient
food that is a component of a mixture in cooking

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