Acetabulum - acteum, vinegar + abrum, holder. Small cup for vinegar, hence any small cup.⏎
Brachiocephalic - brachion, arm; kephale, head.⏎
Axilla - axilla, armpit.⏎
Azygos - azygos, unyoked (not a pair) named for its asymmetry.⏎
Axis - axon, axle or pivot.⏎