pectoralis vs pectoral muscle

pectoralis and pectoral muscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
pectoralis	Yes	No	No	No
pectoral muscle	Yes	No	No	No

As nouns, pectoralis and pectoral muscle are synonyms defined as:

pectoralis and pectoral muscle: either of two large muscles of the chest

Other synonyms of pectoralis include musculus pectoralis, pecs, pectoral.

pectoralis (noun)	pectoral muscle (noun)
either of two large muscles of the chest	either of two large muscles of the chest