"all over" (in reference to dress or armor), 1520s, from Middle French cap-à-pie, literally "head to foot." The more usual French form is de pied en cap. The French words are from Latin caput "head" (from PIE root *kaput- "head") + pedem "foot" (from PIE root *ped- "foot").
he was armed cap-a-pie
capacious
capacitance
capacitate
capacitor
capacity
cap-a-pie
caparison
cape
Cape Cod
capeesh
Capella