Definition
TERMINAL RADAR SERVICE AREA
Airspace surrounding designated airports wherein ATC provides radar vectoring, sequencing, and separation on a full‐time basis for all IFR and participating VFR aircraft. The AIM contains an explanation of TRSA. TRSAs are depicted on VFR aeronautical charts. Pilot participation is urged but is not mandatory.
Source: FAA Pilot/Controller Glossary (verbatim from the Federal Aviation Regulations).