mitten

Mitten comes from Middle English myteyne, borrowed from Old French mitaine, whose own origin is unclear. One guess ties it to 'mite' or 'miste,' a playful old name for a cat, while another traces it to Old High German mittamo, meaning 'half,' itself from a root meaning 'middle' or 'between.'

Mitaine already meant something like a mitten in Old French, and English simply adopted it.

If the 'half' theory is right, mitten shares distant roots with words built on the Proto-Indo-European idea of 'middle' — possibly explaining why a mitten covers only half the fingers, leaving the thumb apart.