canicule vs canicular

canicule is a noun but canicular is not a noun.

Word	Noun	Adjective	Verb	Adverb
canicule	Yes	No	No	No
canicular	No	Yes	No	No

canicule (noun)	canicular (noun)
the hot period between early July and early September; a period of inactivity

canicule (adjective)	canicular (adjective)
	relating to or especially immediately preceding or following the heliacal rising of Canicula (the Dog Star)
	of or relating to the dog days of summer