gastralgia vs stomach ache

gastralgia and stomach ache both are nouns.

Word	Noun	Adjective	Verb	Adverb
gastralgia	Yes	No	No	No
stomach ache	Yes	No	No	No

As nouns, gastralgia and stomach ache are synonyms defined as:

gastralgia and stomach ache: an ache localized in the stomach or abdominal region

Other synonyms of gastralgia include bellyache, stomachache.

gastralgia (noun)	stomach ache (noun)
an ache localized in the stomach or abdominal region	an ache localized in the stomach or abdominal region