thorax vs pectus

thorax and pectus both are nouns.

Word	Noun	Adjective	Verb	Adverb
thorax	Yes	No	No	No
pectus	Yes	No	No	No

As nouns, thorax and pectus are synonyms defined as:

thorax and pectus: the part of the human torso between the neck and the diaphragm or the corresponding part in other vertebrates

Other synonyms of thorax include chest.

thorax (noun)	pectus (noun)
part of an insect's body that bears the wings and legs	the part of the human torso between the neck and the diaphragm or the corresponding part in other vertebrates
the part of the human torso between the neck and the diaphragm or the corresponding part in other vertebrates
the middle region of the body of an arthropod between the head and the abdomen