ἱλάρια

τά
A. hilaria, festival of rejoicing in various cults, e.g. Isis, CIL 12.p.334; esp. of Magna Mater, Jul. Or. 5.168d, Macr. Sat. 1.21.10, Dam. Isid. 131.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project