Hilary m, f
English: from the medieval form of the (post-classical) Latin masculine name Hilarius (a derivative of hilaris cheerful) and its feminine form Hilaria. From the Middle Ages onwards, the name was borne principally by men (in honour of the 4th-century theologian St Hilarius of Poitiers). Now, however, it is more commonly given to girls.
Variant: Hillary.
First names dictionary. 2012.