Sniffer (noun)

1. A device or tool for detecting and analyzing the contents of a data packet in a computer network.
2. A person or animal with a keen sense of smell, especially one trained to detect specific odors.
3. A person who sniffs, especially in an attempt to smell or inhale something.

Origin:

Early 20th century: from sniff + -er, on the pattern of rifler.

Examples:

1. The sniffer was used to detect and isolate the source of the network problem.
2. The sniffer was a valuable tool for security and troubleshooting.
3. The sniffer dog was trained to locate bombs and drugs.
4. The sniffer was able to detect the subtle odor of gasoline.
5. The sniffer was a regular feature at the perfume counter.