smell vs acridity

smell and acridity both are nouns.

Word	Noun	Adjective	Verb	Adverb
smell	Yes	No	Yes	No
acridity	Yes	No	No	No

As nouns, acridity is a hyponym of smell; that is, acridity is a word with a more specific, narrower meaning than smell:

smell: the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form
acridity: having an acrid smell

Other hyponyms of smell include scent, aroma, fragrance, perfume, scent, fetor, foetor, malodor, malodour, mephitis, reek, stench, stink, stank.

smell (noun)	acridity (noun)
the act of perceiving the odor of something	extreme bitterness
any property detected by the olfactory system	the quality of being sharply disagreeable in language or tone
the faculty that enables us to distinguish scents	having an acrid smell
the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form
the general atmosphere of a place or situation and the effect that it has on people

smell (verb)	acridity (verb)
become aware of not through the senses but instinctively
emit an odor
inhale the odor of; perceive by the olfactory sense
smell bad
have an element suggestive (of something)