axillary

The story

1. French · derived fromaxillaire“of the axilla”
2. English todayaxillary

Alteration by association with -ary of the French axillaire (“of the axilla”), itself an alteration of the earlier forms aisselliere and aissellaire, both from the assumed Latin etymon *axillāris, from axilla (“armpit”), diminutive form of the assumed *axula.