tonight vs nowadays

tonight and nowadays both are nouns.

Word	Noun	Adjective	Verb	Adverb
tonight	Yes	No	No	Yes
nowadays	Yes	No	No	Yes

As nouns, nowadays is a hypernym of tonight; that is, nowadays is a word with a broader meaning than tonight:

tonight: the present or immediately coming night
nowadays: the period of time that is happening now; any continuous stretch of time including the moment of speech

Other hypernyms of tonight include present.

tonight (noun)	nowadays (noun)
the present or immediately coming night	the period of time that is happening now; any continuous stretch of time including the moment of speech

tonight (adverb)	nowadays (adverb)
during the night of the present day	in these times