yolky - n.
1 the yellow internal part of an egg that nourishes the young before it hatches.
2 Biol. the corresponding part of any animal ovum.

yolk-bag (or -sac) a membrane enclosing the yolk of an egg.

yolked adj. (also in comb.). yolkless adj. yolky adj. [OE geol(o)ca f. geolu YELLOW]