Definition of pied d'éléphant in English:
pied d'éléphant
(also pied d'elephant)
noun ˌpjeɪ ˌdɛlɪˈfɒ̃ˌpjɛ ˌdɛlɪˈfɒ̃
A padded sack used to protect the lower part of the body when sleeping outdoors in a bivouac.
Origin
1950s; earliest use found in Charles Evans (1918–1995), surgeon and mountaineer. From French pied d'éléphant from pied foot + de + éléphant.