dagger

English dagger comes from Middle English daggere, probably from Old French dague, a word found across Europe (Occitan, Italian, Spanish daga, Dutch dagge, German Degen) whose deeper source no one agrees on — Grimm guessed Celtic, others a lost Vulgar Latin *daca meaning 'Dacian knife,' and OED notes it might instead trace to an English verb dag, 'to stab.'

The word has meant a short stabbing blade since it entered English in the 1380s, with Middle Latin scribes writing versions like daga and dagarius as they tried to capture the same weapon in their own records.

Some scholars connect dagger to Ancient Greek thēgō, 'to sharpen, whet,' suggesting an ancient root shared with the idea of honing an edge, though this link is only a proposal, not a certainty.