egg is from Middle English, from Old Norse, replacing an earlier English word ey. Both are of Germanic origin but probably go back to a PIE root *owyo-, which also gave us Latin ovum and Ancient Greek oon, as well as cognates in other languages. Intriguingly there is even a hint of a connection with *awi- "bird" and perhaps even further back to a word that meant "clothed" (birds are clothed in feathers , you see).
yolk is from yellow, OE geolu + a suffix which might be -ca, a diminutive (so "small yellow") or -ock, or something else: there seems no general agreement. And yellow? It is probably from a PIE root *ghel-, "shining", and so perhaps connected with gleam and glisten and a number of other words starting with gl- and semantically related to brightness or shining.
Here is an interesting Old English passage from Aelfric's Catholic Homilies, about 990 CE, in which he uses the analogy of an egg to how how two distinct things can be part of a single whole.
Sceawa nu on anum æge, hu þæt hwite ne bið gemengd to ðam geolcan, & bið hwæðere an æg.
"Look now at an egg, how the white is not mixed with the yolk, and yet it is one egg." (Chat GPT 5)
A Little "Eggymology"
egg is from Middle English, from Old Norse, replacing an earlier English word ey. Both are of Germanic origin but probably go back to a PIE root *owyo-, which also gave us Latin ovum and Ancient Greek oon, as well as cognates in other languages. Intriguingly there is even a hint of a connection with *awi- "bird" and perhaps even further back to a word that meant "clothed" (birds are clothed in feathers , you see).
yolk is from yellow, OE geolu + a suffix which might be -ca, a diminutive (so "small yellow") or -ock, or something else: there seems no general agreement. And yellow? It is probably from a PIE root *ghel-, "shining", and so perhaps connected with gleam and glisten and a number of other words starting with gl- and semantically related to brightness or shining.
Here is an interesting Old English passage from Aelfric's Catholic Homilies, about 990 CE, in which he uses the analogy of an egg to how how two distinct things can be part of a single whole.
"Look now at an egg, how the white is not mixed with the yolk, and yet it is one egg." (Chat GPT 5)