crab vs grump

crab and grump both are nouns.

Word	Noun	Adjective	Verb	Adverb
crab	Yes	No	Yes	No
grump	Yes	No	No	No

As nouns, grump is a hypernym of crab; that is, grump is a word with a broader meaning than crab:

Other hypernyms of crab include churl, crank, crosspatch, grouch.

crab (noun)	grump (noun)
a stroke of the oar that either misses the water or digs too deeply	a bad-tempered person
decapod having eyes on short stalks and a broad flattened carapace with a small abdomen folded under the thorax and pincers
a louse that infests the pubic region of the human body
the edible flesh of any of various crabs
a quarrelsome grouch

crab (verb)	grump (verb)
complain
fish for crab
scurry sideways like a crab
direct (an aircraft) into a crosswind