'Gnathostomata' originates from New Latin, ultimately from Greek 'gnāthostóma' where 'gnath-' meant 'jaw' and 'stoma' meant 'mouth'.

'Gnathostomata' developed as a taxonomic plural in New/Modern Latin from the Greek root 'gnāthostóma' and was adopted into scientific English usage as the name of the clade.

Initially it literally referred to 'jawed mouths' in Greek, but over time it came to denote the taxonomic group of 'jawed vertebrates' in modern biology.