| Acronym | Definition |
|---|
| PhD | Philosophiae Doctor (doctor of philosophy) |
| PhD | Psychology and Human Development (various organizations) |
| PhD | Pizza Hut Delivery (Indonesia) |
| PhD | Piled Higher and Deeper |
| PhD | Public Health District (various locations) |
| PhD | Professional Hair Dresser |
| PhD | Presbyterian Hospital of Dallas |
| PhD | Pure Hard Dance |
| PhD | Palm Hills Developments (real estate; Egypt) |
| PhD | Portable Hard Drive |
| PhD | Pre-Historic Dinosaur |
| PhD | Pocket Hard Disk |
| PhD | Portable Handheld Development |
| PhD | Portable Hard Disk |
| PhD | Potential Heavy Drinker |
| PhD | Post Hole Digger (construction) |
| PhD | Pretty Hot Dude (brand) |
| PhD | Pull Him/Her Down (Internet slang) |
| PhD | Prolyl Hydroxylase (protein) |
| PhD | Private Hire Driver (UK) |
| PhD | Port Huron & Detroit (railroad; Michigan) |
| PhD | Pleckstrin Homology Domain (biochemistry) |
| PhD | Plant Homeodomain (microbiology) |
| PhD | Port Hueneme Division (US Naval Surface Warfare Center) |
| PhD | Poly-Harmonic Distortion |
| PhD | Piled High in Debt |
| PhD | Peak Hourly Demand (measurment; various locations) |
| 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 | Pizza Hut Dude |
| PhD | Poor Helpless and Desperate |
| PhD | Phenomenally Dumb |
| PhD | Phased-History Data |
| 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 | Professional Hole Digger |
| PhD | Punjab Haryana and Delhi (India) |
| PhD | Phase History Data |
| PhD | Process Hierarchy Diagram (business process modelling) |
| PhD | Parametric High Definition |
| PhD | Poor Hungry Doctor |
| PhD | Pathfinder Healthcare Developments (Smethwick, West Midlands, UK) |
| PhD | Pothole Dodger (driver on poorly maintained roads) |
| PhD | Port Huron & Detroit Railroad |
| 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 |