crab

Crab comes from Middle English crabbe, from Old English crabba, which traces back through Proto-West Germanic and Proto-Germanic *krabbô to a Proto-Germanic verb meaning "to scratch." That in turn goes back to a Proto-Indo-European root, *gerbʰ-, meaning "to carve, scratch."

The word has stayed remarkably close to its roots — Old English crabba already meant both the crustacean and, notably, cancer, a sense that survives in the disease's name today.

It shares a root with English carve, both descending from the same Proto-Indo-European scratching-and-carving idea. It's also distantly linked to creep, through Germanic cousins like German krabbeln ("to crawl") and Dutch krabbelen ("to scratch").