breathe in vs snuff

breathe in is not a noun while snuff is a noun.

Word	Noun	Adjective	Verb	Adverb
breathe in	No	No	Yes	No
snuff	Yes	Yes	Yes	No

As verbs, snuff is a hyponym of breathe in; that is, snuff is a word with a more specific, narrower meaning than breathe in:

Other hyponyms of breathe in include aspirate, sniff, sniffle, snivel, snuffle, drag, draw, puff, huff, snort.

breathe in (noun)	snuff (noun)
	sensing an odor by inhaling through the nose
	finely powdered tobacco for sniffing up the nose
	a pinch of smokeless tobacco inhaled at a single time
	the charred portion of a candlewick

breathe in (adjective)	snuff (adjective)
	snuff colored; of a greyish to yellowish brown

breathe in (verb)	snuff (verb)
draw in (air)	inhale (something) through the nose
	sniff or smell inquiringly