σιγμοειδής

ές, Adv.
A. of the shape of sigma (<*>), crescent-shaped, semicircular, ἀπόφυσις Gal. UP 13.12; of the moon, Cleom. 2.5. Adv. σιγμοειδῶς Heliod. ap. Orib. 49.8.6.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project