Noun
the yellow spherical part of an egg that is surrounded by the albumen
Source: WordNetegg-yolk
I'm frightened of eggs, worse than frightened, they revolt me. That white round thing without any holes have you ever seen anything more revolting than an egg yolk breaking and spilling its yellow liquid Blood is jolly, red. But egg yolk is yellow, revolting. I've never tasted it. Alfred Hitchcock
Egg yolk is never used by itself with pigment; it dries almost immediately and crackles when it is dry. Source: Internet