A person or animal that detects odors; a device used to detect or analyze gases, chemicals, or network traffic.
From 'sniff' plus agent suffix '-er.' 'Sniff' comes from Middle English, likely imitative of the sound. The technological meaning emerged in the late 20th century with computer networking.
Airport security uses both biological sniffers (trained dogs) and electronic sniffers (chemical detection devices) to find contraband - dogs can detect scents at concentrations nearly 100 million times lower than humans can perceive. In cybersecurity, packet sniffers intercept digital communications much like eavesdropping on conversations.
Complete word intelligence in one call. Free tier — 50 lookups/day.