From Old French coustume, from a Vulgar Latin *cōnsuētūmen or *costūmen, from Latin cōnsuētūdinem, accusative singular of cōnsuētūdō (“custom, habit”), from cōnsuēscō (“accustom, habituate”), from con- (“with”) + suēscō (“become used or accustomed to”). First element con- derives from cum, from Old Latin com, from Proto-Italic *kom, from Proto-Indo-European *ḱóm (“with, along”). Second element suēscō is from Proto-Indo-European *swe-dʰh₁-sk-, from *swé (“self”) + *dʰeh₁- (“to put, place, set”); related to Latin suus (“one's own, his own”). Compare also Medieval Latin costuma. Doublet of costume and consuétude. Cognate with Spanish costumbre, Catalan costum.
coutume f (plural coutumes)