Plain English Meaning
Weather updates sent to the cockpit electronically while you're flying, so you can see things like radar, storms, and forecasts on a screen instead of only hearing them over the radio.
Full Definition
Weather information transmitted to an aircraft in flight through a digital data connection, typically via satellite or ground-based radio broadcast, and displayed in the cockpit on a multifunction display, electronic flight bag, or compatible tablet. Common products include radar mosaics, METARs, TAFs, AIRMETs, SIGMETs, winds aloft, PIREPs, and .