uncle vs great-uncle

uncle and great-uncle both are nouns.

Word	Noun	Adjective	Verb	Adverb
uncle	Yes	No	No	No
great-uncle	Yes	No	No	No

As nouns, great-uncle is a hyponym of uncle; that is, great-uncle is a word with a more specific, narrower meaning than uncle:

Other hyponyms of uncle include granduncle.

uncle (noun)	great-uncle (noun)
the brother of your father or mother; the husband of your aunt	an uncle of your father or mother
a source of help and advice and encouragement