PSR

Short definition from Wiktionary

Noun

1. 1
   Abbreviation of pulsar.
2. 2
   Initialism of primary surveillance radar.
3. 3
   Initialism of police service representative, an LAPD dispatcher.
4. 4
   Initialism of pre-sentence report.
5. 5
   Initialism of point of safe return.
6. 6
   Initialism of permanently shadowed region
7. 7
   Initialism of precision sniper rifle

Proper noun

1. 1
   Initialism of Philmont Scout Ranch.