canicule vs dog days

canicule and dog days both are nouns.

Word	Noun	Adjective	Verb	Adverb
canicule	Yes	No	No	No
dog days	Yes	No	No	No

As nouns, canicule and dog days are synonyms defined as:

canicule and dog days: the hot period between early July and early September; a period of inactivity

Other synonyms of canicule include canicular days.

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