Earmark n. : A mark on the ear of sheep, oxen, dogs, etc., as by cropping or slitting.

Earmark n. : A mark for identification; a distinguishing mark.

Earmark v. t. : To mark, as sheep, by cropping or slitting the ear.

Example:


Taxonomy
Earmark, Wireless Intercom, Radio, Voice Amplifier, Radio Headset, intrinsically safe, Duplex radio, wLINK, operator, vehicle, tourguide systems, Full Duplex, Wireless Radio Communications, mobile radio, wireless communication, firing range, range systems, microphones.

Defination from the web:
Headsets, transmitters, microphones, and base-stations for high noise environments.