Definitions:

1. An electronic amplification system used as a communication system in public areas. NOUN
   • The amusement park's PA system played upbeat music to create a festive atmosphere.
2. An electronic system used to amplify and distribute sound so it can be heard clearly by a large audience or in a public space. NOUN
   • The concert's PA system ensured the band's music could be heard by thousands of fans.
3. Short for Public Address System. NOUN
   • The principal used the PA system to make morning announcements to the entire school.

Synonyms:

• amplification system
• public address system
• sound system