PSO
- Active Directory
- Antonio Nariño Airport
- Counter-insurgency
- Federal Aviation Administration
- ICANN
- Location identifier
- National Marrow Donor Program
- PSO J318.5-22
- PSO-1
- Pacific Symphony Orchestra
- Pakistan State Oil
- Particle swarm optimization
- Patient safety organization
- Penalty shootout
- Peoria Symphony Orchestra
- Perth Symphony Orchestra
- Phantasy Star
- Phantasy Star Online
- Phase-shift oscillator
- Pittsburgh Symphony Orchestra
- Plano Symphony Orchestra
- Portland Symphony Orchestra
- Producers Sales Organization
- Projective special orthogonal group
- Protective services officer
- Psoriasis
- Public Service Company of Oklahoma
- Public service obligation
- Puro Sangue Orientale
- Stevens Field