sniff / snif/ • v. [intr.] draw in air audibly through the nose to detect a smell, to stop it from running, or to express contempt: his dog sniffed at my trousers| [with direct speech] “You're behaving in an unladylike fashion,” sniffed Mother. ∎ [tr.] draw in (a scent, substance, or air) through the nose. ∎ (sniff at) show contempt or dislike for: the price is not to be sniffed at. ∎ (sniff around) inf. investigate covertly, esp. to find out confidential or incriminating information about someone. ∎ [tr.] (sniff something out) inf. discover something by investigation: he made millions upon millions sniffing out tax loopholes for companies.• n. an act or sound of drawing air through the nose: he gave a sniff of disapproval. ∎ an amount of air or other substance taken up in such a way: his drug use was confined to a sniff of amyl nitrite. ∎ [in sing.] inf. a trace, hint, or small amount: they're off at the first sniff of trouble.