'gigas' originates from Ancient Greek, specifically the word 'γίγας (gígas)', where the root meant 'giant'.

'γίγας' was borrowed into Latin as 'gigas' and later adopted into New Latin/scientific Latin, where it became widely used as a species epithet in biological nomenclature (e.g. Crassostrea gigas).

Initially it meant 'giant' in Ancient Greek; over time it has retained that core meaning but is now mainly encountered in scientific names to denote large size rather than as a general English adjective.