"Olfaction" is the ability to smell. ("Olfaction" has Latin roots that literally mean "smell making," which explains why it looks like other words about making things, like "factory.")
So, something olfactory involves the sense of smell.
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Part of speech:
Adjective: "an olfactory delight," "the sharpest part of that memory is olfactory."
The noun is "olfaction," the adverb is "olfactorily," and an alternate adjective that means the same thing as "olfactory" is "olfactive."
And the adjective "olfactible" means "able to be smelled: giving off a smell." Cool, right? Let's file that one in the memory banks along with "visible," "audible," "tasteable," and "tangible."
How to use it:
This word has a formal tone. You'll see it in medical contexts--"olfactory bulb," "olfactory nerve"--but it's also appropriate for general contexts.
Talk about olfactory senses and abilities; olfactory delights and sensations; olfactory memories and experiences; olfactory presences, properties and manifestations; even olfactory hallucinations.
examples: "There’s not much to smell in a winter pasture. There actually is, of course, I just can’t register it, and I think for the millionth time that, at least on an olfactory level, a dog’s life is infinitely more interesting than mine."
— Callan Wink, The New Yorker, 13 August 2018
"A prop guy went to the cafeteria and emptied all the food that had been left on plates into a bucket, which they would then pour onto the unsuspecting actor. But they ran out of time that day and couldn't shoot the scene until a week later... They dumped [the bucket] on the kid anyway. Pretty much everyone within olfactory range was disgusted to some extent or another."
— Adam Clair, The Verge, 23 August 2017