generated at
sniff

verb no object
draw in air audibly through the nose to detect a smell, to stop it from running, or to express contempt:
«…の» においを(くんくん)かぐ «at» ; (鼻をふんふんいわせて)息を吸い込む; 〖~(around [about]) for A〗 (においをかいで)A〈目的の物〉を探して回る; 鼻をすする (!かぜや泣いたときなど)
e.g. his dog sniffed at my trousers
⦅書⦆ 〖直接話法〗…と鼻であしらって不満そうに言う
e.g. with direct speech : “You're behaving in an unladylike fashion,” sniffed Mother.
with object draw in (a scent, substance, or air) through the nose.
…のにおいをかぐ; 〈香り〉をかぐ; 〈空気など〉を(鼻から)吸い込む; ⦅俗⦆ 〈麻薬・シンナーなど〉を鼻から吸い込む(up)
usually with negative (sniff at) show contempt or dislike for:
〖~ at A〗 Aを鼻であしらう (!不承認・軽蔑などを表すしぐさ)
e.g. the price is not to be sniffed at.
(sniff around) informal investigate covertly, especially to find out confidential or incriminating information about someone.
⦅くだけて⦆ (情報・秘密などを求めて)かぎまわる
with object (sniff something out) informal discover something by investigation:
〈警察犬などが〉〈爆発物・麻薬など〉を(においをかいで)見つける(out); ⦅くだけて⦆ 〈情報・秘密など〉をかぎつける, 見つけだす(out)
e.g. he made millions upon millions sniffing out tax loopholes for companies.

noun
an act or sound of drawing air through the nose:
鼻で吸うこと[音], 鼻をすすること[音]; におい(をかぐこと); 鼻であしらうこと
e.g. he gave a sniff of disapproval.
an amount of air or other substance taken up through the nose:
⦅英・くだけて⦆ ; 〖a [the] ~ of A〗 わずかなA, Aの兆候
e.g. his drug use was confined to a sniff of amyl nitrite.
in singular informal a trace, hint, or small amount:
e.g. they're off at the first sniff of trouble.
in singular informal a small chance:
e.g. the Olympic hosts will at least get a sniff at a medal.

ORIGIN
Middle English: imitative.