yolk

Most people know the yolk as the yellow or orange part inside an egg. It is the rich, soft part that feeds the young bird as it grows before hatching. In everyday life, people usually talk about it when cooking or eating eggs, such as a fried egg with a runny yolk or a boiled egg with a firm yolk.

The word is mainly used in this egg-related sense. It comes from the Old English geolca, a word linked to "yellow." So when you crack an egg and see that golden center, you are looking at a very old word that has stayed close to its original meaning.

The most common meaning of "yolk" is the yellow inner part of a bird's egg. It contains stored food that helps the embryo develop before the chick hatches. In cooking, it is known for its rich taste and soft texture, and people often talk about whether the yolk is runny, firm, broken, or bright in color.

This is the meaning almost everyone uses in normal English. You might read it in recipes, food writing, science lessons, or everyday conversation about eggs. For example, someone might say, "I like my yolk soft," or "Be careful not to break the yolk." The word can also be used in biology when talking about eggs from birds and other animals.

There is also a less common technical meaning in wool production. In that context, "yolk" can mean the natural greasy substance in sheep's wool. That use exists, but many English learners will rarely see it compared with the egg meaning.

The word comes from the Old English geolca, meaning the yellow part of an egg. That history fits the modern meaning closely. In short, "yolk" is mainly a simple, concrete word for the nourishing yellow part inside an egg, with a rare extra use in the language of wool.