YOLK
yolk, vitellus
(noun) nutritive material of an ovum stored for the nutrition of an embryo (especially the yellow mass of a bird or reptile egg)
Source: WordNet® 3.1
Etymology
Noun
yolk (countable and uncountable, plural yolks)
The yellow, spherical part of an egg that is surrounded by the white albumen, and serves as nutriment for the growing young.
The grease in a sheep's fleece.
Source: Wiktionary
Yolk, n. Etym: [OE. yolke, yelke, ýolke, ýelke, AS. geoloca, geoleca,
fr. geolu yellow. See Yellow.] [Written also yelk.]
1. The yellow part of an egg; the vitellus.
2. (Zoöl.)
Definition: An oily secretion which naturally covers the wool of sheep.
Yolk cord (Zoöl.), a slender cord or duct which connects the yolk
glands with the egg chambers in certain insects, as in the aphids.
– Yolk gland (Zoöl.), a special organ which secretes the yolk of
the eggs in many turbellarians, and in some other invertebrates. See
Illust. of Hermaphrodite in Appendix.
– Yolk sack (Anat.), the umbilical vesicle. See under Unbilical.
Source: Webster’s Unabridged Dictionary 1913 Edition