From The Collaborative International Dictionary of English v.0.48 [gcide]:
Capapie \Cap`*a*pie"\, adv. [OF. (?) cap-a-pie, from head to
foot, now de pied en cap from foot to head; L. pes foot +
caput head.]
From head to foot; at all points. "He was armed cap-a-pie."
--Prescott.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
cap-a-pie
adv 1: at all points from head to foot; "he was armed cap-a-pie"
[syn: cap-a-pie, from head to toe]