| Abbreviation | Definition |
|---|---|
| PSH | Partridge, Snow, & Hahn, L. L. P. |
| PSHL | Property Services Haslemere Ltd |
| PSI | Paleontology Studies Incorporation |
| PSI | Patient Services Inc |
| PSI | Personnel Staffing Inc |
| PSI | Physical Sciences Inc |
| PSI | Polymer Systems Inc |
| PSI | Polymer Systems Incorporated |
| PSI | Power Solutions International |
| PSI | Praeger Security International |
| PSI | Pressure Systems Incorporated |
| PSI | Printers & Stationers, Inc. |
| PSI | Production Services International |
| PSI | Professional Service Inc |
| PSI | Professional Service Incorporated |
| PSI | Professional Service Industries |
| PSI | Publisher Services Inc |
| PSI | Publisher Services Incorporated |
| PSI | Pure Style Incorporated |
| PSIC | Pacific Specialty Insurance Company |