Other forms: lairs
A lair is the resting place of a wild animal. A wolf's lair, return to its lair, hunted to its lair.
It is used of predators rather than of prey — foxes and wolves have lairs, rabbits have burrows. In stories, the villain's lair is a fixed idea and usually contains machinery. Note that lair comes from the same root as lie and layer, so a lair is simply a place to lie down; and that in Scots a lair is a burial plot, which is the same word applied more finally.
Old English leger meant a bed or couch, from licgan, to lie — the same root as lie, lay and layer. A lair is a lying-down place and nothing more sinister than that.
Proto-Indo-European
*legʰ-
Proto-Germanic
*legrą
Old English
leġer — couch, bed
Middle English
leir
English, today
lair
From Middle English leir, leire, lair, lare, from Old English leġer (“couch, bed”), from Proto-Germanic legrą, from Proto-Indo-European legʰ-.
Etymology from Wiktionary, CC BY-SA