vallecula vs fissure

vallecula and fissure both are nouns.

Word	Noun	Adjective	Verb	Adverb
vallecula	Yes	No	No	No
fissure	Yes	No	Yes	No

As nouns, fissure is a hyponym of vallecula; that is, fissure is a word with a more specific, narrower meaning than vallecula:

vallecula: (anatomy) any furrow or channel on a bodily structure or part
fissure: (anatomy) a long narrow slit or groove that divides an organ into lobes

Other hyponyms of vallecula include costal groove.

vallecula (noun)	fissure (noun)
(anatomy) any furrow or channel on a bodily structure or part	(anatomy) a long narrow slit or groove that divides an organ into lobes
	a long narrow cleft
	a long narrow depression in a surface

vallecula (verb)	fissure (verb)
	break into fissures or fine cracks