This is the 4358th most frequent Japanese word.
卵黄
Egg yolk.
卵黄 is used to refer to the yolk of an egg.
卵黄の色が濃いほど新鮮です。
The darker the yolk color, the fresher it is.
卵黄 is specifically referring to a quantitative use of egg yolks in a recipe.
ケーキのレシピに卵黄を2個使用します。
The cake recipe uses two egg yolks.
卵黄 is contrasted with 卵白 (egg white) to distinguish the parts of an egg.