| Noun | 1. | P.A. - an electronic amplification system used as a communication system in public areasamplifier - electronic equipment that increases strength of signals passing through it communication system - a system for communicating loudspeaker, loudspeaker system, speaker system, speaker unit, speaker - electro-acoustic transducer that converts electrical signals into sounds loud enough to be heard at a distance tannoy - a loudspeaker |
| Adv. | 1. | p.a. - by the year; every year (usually with reference to a sum of money paid or received); "he earned $100,000 per annum"; "we issue six volumes per annum" |