Merriam-Webster's Collegiate® Dictionary, 11th Edition
CLOAK
I. noun
Etymology: Middle English cloke, from Anglo-French cloque bell, cloak, from Medieval Latin clocca bell; from its shape
Date: 13th century
a loose outer garment, something likened to an outer garment: as, something that envelops or conceals , a distinctive character or role ,
II. transitive verb
Date: 1509
to cover or hide with or as if with a cloak, see: disguise