Plain English Meaning
A set of weather instruments at an airport that takes readings on its own and reads them out over the radio so pilots can hear current conditions before landing or taking off.
Full Definition
An unmanned, automated suite of weather sensors installed at or near an airport that continuously measures local weather conditions and broadcasts them to pilots by radio and, at many sites, by telephone. Typical AWOS reports include altimeter setting, wind direction and speed, temperature, dew point, , , and , with the elements depending on the AWOS (AWOS-A, AWOS-1, AWOS-2, , and variants).