Plain English Meaning
A radio frequency at smaller airports where pilots talk to someone on the ground — usually staff at the airport business — to get basic airport information like which runway is in use and what the wind is doing.
Full Definition
A non-government air-ground radio communication station that may provide airport advisory information at certain airports. UNICOM is operated by a private agency at the airport (typically the fixed-base operator) and provides information such as wind, favored runway, known traffic, and field conditions. UNICOM is not an air traffic control service and cannot issue clearances or instructions.