intransitive verb

1. to draw in air through the nose with enough force to be heard, as in clearing the nose or smelling something
2. to express disdain, skepticism, etc. by sniffing

Etymology: ME sniffen, akin to Dan snive, of echoic orig.

transitive verb

1. to breathe in forcibly through the nose; draw in or inhale nasally
2. to smell (a substance) by sniffing
3. to detect, perceive, or get a suspicion of by or as by sniffing: often with out

noun

1. an act or sound of sniffing
2. something sniffed