infrequent vs rare

infrequent and rare both are adjectives.

Word	Noun	Adjective	Verb	Adverb
infrequent	No	Yes	No	No
rare	No	Yes	No	No

infrequent (adjective)	rare (adjective)
not frequent; not occurring regularly or at short intervals	marked by an uncommon quality; especially superlative or extreme of its kind
	recurring only at long intervals
	(of meat) cooked a short time; still red inside
	not widely distributed
	having low density
	not widely known; especially valued for its uncommonness