| Acronym | Definition |
|---|
| PhD | Philosophiae Doctor (doctor of philosophy) |
| PHD | Presbyterian Hospital of Dallas |
| PHD | Portable Hard Drive |
| PHD | Post Hole Digger (construction) |
| PHD | Prolyl Hydroxylase (protein) |
| PHD | Pleckstrin Homology Domain (biochemistry) |
| PHD | Plant Homeodomain (microbiology) |
| PHD | Port Hueneme Division (US Naval Surface Warfare Center) |
| PHD | Permanent Head Damage (slang) |
| PHD | Push Here Dummy (point & shoot cameras) |
| PHD | Professional Help Desk |
| PHD | Probability Hypothesis Density |
| PHD | Pulse Height Distribution (ion detection) |
| PHD | Personal Hemodialysis System (Aksys, Ltd.) |
| PHD | Pacific Health Dialog |
| PHD | Phenomena in High Dimensions |
| PHD | Portable Handheld Device |
| PHD | Post Holiday Depression |
| PHD | Pre-Hearing Detention |
| PHD | Plumbing Hardware Dispatcher (Google TiSP spoof) |
| PHD | Process Historian Database |
| PHD | Pisarenko Harmonic Decomposition |
| PHD | Player Hater Degree |
| PHD | Punjab Haryana and Delhi (India) |
| PHD | Phase History Data |
| PHD | Process Hierarchy Diagram (business process modelling) |
| PhD | Poor Hungry Doctor |
| PHD | Parametric High Definition |
| PHD | Port Huron & Detroit Railroad |
| PhD | Pothole Dodger (driver on poorly maintained roads) |
| Phd | Pathfinder Healthcare Developments (Smethwick, West Midlands, UK) |
| PHD | People Helping the Disabled (Edmonds, Washington) |
| Phd | Post Homicidal Depression (serial killers) |
| PHD | Production Hole Diameter |
| PHD | Praising Him Daily |
| PHD | Public High Diploma |
| PHD | Pray Hard Daily |
| PHD | Psychology and Human Development (various organizations) |
| PhD | Piled High in Debt |
| PHD | Poly-Harmonic Distortion |
| PHD | Phased-History Data |