Webster's Revised Unabridged Dictionary · 1913

Sniff

Sniff , intransitive verb

[Old English sneven; akin to snivel, snuff; compare Danish snive to sniff. See Snuff, transitive verb]

To draw air audibly up the nose; to snuff; -- sometimes done as a gesture of suspicion, offense, or contempt.
So ye grow squeamish, gods, and sniff at heaven. — M. Arnold

Sniff , transitive verb

1.
To draw in with the breath through the nose; as, to sniff the air of the country.
2.
To perceive as by sniffing; to snuff, to scent; to smell; as, to sniff danger.

Sniff , noun

The act of sniffing; perception by sniffing; that which is taken by sniffing; as, a sniff of air.