moor

Moor comes from Middle English mor, from Old English mōr, tracing back through Proto-West Germanic *mōr and Proto-Germanic *mōraz to Proto-Indo-European *móri.

The word's deep root, *móri, is the same one behind words for 'sea' in other languages — though in English it settled into meaning open, boggy wasteland rather than water.

It's cognate with Welsh môr and Old Irish muir, both meaning 'sea,' as well as Dutch moer and German Moor — and it shares a root with the English word mere.