Plain English Meaning
A short, coded weather snapshot of an airport, put out about once an hour, telling you what the weather is doing right now at that field.
Full Definition
A standardized observation of current weather conditions at an airport, issued on a regular schedule (typically once per hour) and formatted in a coded sequence that reports wind, visibility, weather phenomena, sky condition, temperature, dew point, and altimeter setting. It is the primary source of observed surface weather used by pilots for and in- .