| Acronym | Definition |
|---|
| PEN | Penitentiary |
| PEN | Penalty |
| PEN | Peruvian Nuevo Sol (Currency) |
| PEN | Pendleton (Amtrak station code; Pendleton, OR) |
| PEN | Public Education Network |
| PEN | Poder Ejecutivo Nacional (Argentina) |
| PEN | Polyethylene Naphthalate (electrical insulation material) |
| PEN | Pan European Network (air traffic management) |
| PEN | Programa Estado de la Nación (Spanish: State of the Nation Program; Costa Rica) |
| PEN | Personal Electronic Navigator |
| PEN | Project on Emerging Nanotechnologies |
| PEN | Poverty Environment Nexus (various locations) |
| PEN | Partido Encuentro Nacional (Paraguay) |
| PEN | Poets, Playwrights, Editors, Essayists, and Novelists |
| PEN | Personal Education Number |
| PEN | Pennsylvania Environmental Network |
| PEN | Penetrating/Penetration |
| PEN | Private Enterprise Number (assigned by the IANA) |
| PEN | Peer Education Network |
| PEN | Parent Empowerment Network (Washington state) |
| PEN | Prison Enterprises Network (Indiana) |
| PEN | Program Element Number |
| PEN | Penang, Malaysia - Penang International (Airport Code) |
| PEN | Pilipino Educators Network (Maryland) |
| PEN | Positive-Electrolyte-Negative (solid oxide fuel cells) |
| PEN | Plain English Network (US government) |
| PEN | Permanent Employee Number |
| PEN | Professional Employer Network |
| PEN | Primary Endosperm Nucleus |
| PEN | Persuasive, Expository, Narrative (basic styles of writing) |
| PEN | Protective Earth and Neutral (conductor) |
| PEN | Provinciaal Energiebedrijf NoordHolland (Dutch) |
| PEN | Professional Executive Network |
| PEN | Private Electronic Network |
| PEN | Poets, Editors, Novalists |
| PEN | Phoenix Entrepreneurs Network (Phoenix, AZ) |
| PEN | Probability, Electric Strength, Number of Life Cycles |