A rare word today, but a nice one, one that conjures up images of a warm and cosy hearth. This is not an easy word to trace. It came into English from Scottish English, where was generally used to mean “hearthside”, around the 18th century.
It is made up of two parts; ingle+nook. The first part of the word is likely to have evolved from the Gaelic word aingeal. In Scots Gaelic this means “fire” or “light”, and also in Irish Gaelic, this word means “glowing coal”. Both meanings are obviously related, and give us the “hearth” part of “inglenook”.
The second part of the word, -nook, meant “corner” or “angle”. We can find it in Middle English from around 1300 onwards. Here it is in the Castleford Chronicle, from around 1420:
ffour kindes of fische in þe four nokes.
(four kinds of fish in the four corners).
Note the form at that time; noke. I feel that this is significantly different from the word that is sometimes suggested as its forebear in Old English: hnecca, which meant neck, and I am reluctant to connect it to that root. I think it is more honest to state simply that we cannot be certain of the origin beyond noke.