sniff

Sniff, as a verb and noun, refers to drawing air through the nose to perceive a smell, or to the sense of smell itself. As a verb, sniff often conveys a quick, sometimes audible inhalation. The noun can refer to a brief act of sniffing, or to the odor that has been sniffed. The term is generally onomatopoeic, reflecting the sound and feel of the act of inhaling.

In biology and behavior, sniffing is a primary olfactory activity. Humans and animals sample the environment by sniffing; dogs in particular rely on scent to navigate, track, and identify substances. Olfactory sensitivity and sniffing behavior can vary with age, health, and context. Medical contexts may include olfactory testing to assess sense of smell.

Common expressions include "to sniff at" meaning to show disdain or rejection, "to sniff out" meaning to discover or detect, and "sniff test" used as a quick informal check of plausibility or quality of a plan.

Colloquially, sniff can refer to the act of inhaling intoxicants or solvents through the nose. Sniffing such substances can produce rapid effects, but poses significant health risks and is illegal in many jurisdictions.

In technology, packet sniffing describes the process of capturing and analyzing network traffic. Sniffers or sniffing tools, such as Wireshark or tcpdump, are used for network management, debugging, and security auditing. When used without authorization, sniffing can violate privacy and laws.