名詞 yolk:

1. the yellow spherical part of an egg that is surrounded by the albumen
   同義詞：egg yolk
2. nutritive material of an ovum stored for the nutrition of an embryo (especially the yellow mass of a bird or reptile egg)
   同義詞：vitellus

1. The egg has a double yolk.
   這只蛋雙黃。
2. One of two spiral bands of tissue in an egg that connect the yolk to the lining membrane at either end of the shell.
   卵黃系帶雞蛋內(nèi)將蛋黃和蛋殼任一端的內(nèi)膜連接的兩個螺旋的帶狀組織之一
3. The yolk is the yellow part in an egg.
   蛋黃是雞蛋中的黃色部分。

yolk

n.（名詞）

The yellow, usually spherical portion of an egg of a bird or reptile, surrounded by the albumen and serving as nutriment for the developing young.
蛋黃：鳥類或爬行動物蛋內(nèi)的黃色的、通常是球形的部分，回周包有蛋白，作為哺育幼鳥（仔）的營養(yǎng)物
A corresponding portion of the egg of other animals, consisting of protein and fat which serve as the primary source of nourishment for the early embryo and protoplasmic substances from which the embryo develops.
卵黃：其它動物蛋內(nèi)的相應(yīng)部分，由蛋白質(zhì)和脂肪組成，用作早期胚胎的主要營養(yǎng)來源和胚胎由此發(fā)育的原生物質(zhì)
A greasy substance found in unprocessed sheep`s wool.
羊毛油脂：未加工羊毛中的油膩物質(zhì)

來源：
Middle English yolke
中古英語 yolke
from Old English geolca
源自 古英語 geolca
from geolu [yellow] * see yellow
源自 geolu [黃色的] *參見 yellow

【引伸】
yolk.y
adj.（形容詞）