ab vs skeletal muscle

ab and skeletal muscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
ab	Yes	No	No	No
skeletal muscle	Yes	No	No	No

As nouns, skeletal muscle is a hypernym of ab; that is, skeletal muscle is a word with a broader meaning than ab:

ab: the muscles of the abdomen
skeletal muscle: a muscle that is connected at either or both ends to a bone and so move parts of the skeleton; a muscle that is characterized by transverse stripes

Other hypernyms of ab include striated muscle.

ab (noun)	skeletal muscle (noun)
the muscles of the abdomen	a muscle that is connected at either or both ends to a bone and so move parts of the skeleton; a muscle that is characterized by transverse stripes