Plain English Meaning
A radio broadcast pilots could tune in while flying to hear a recorded summary of dangerous weather in the area. It has been retired, but pilots still see it referenced in older charts, handbooks, and study materials.
Full Definition
A continuous broadcast service, formerly transmitted over selected VOR frequencies, that provided pilots in flight with recorded summaries of significant weather hazards such as AIRMETs, SIGMETs, Convective SIGMETs, Center Weather Advisories, severe weather forecast alerts, and urgent pilot reports. HIWAS was discontinued by the in January 2020; its function is now served by -Broadcast (FIS-B) and with .