Hal·ley 
(hălē), Edmund or Edmond 1656-1742.
(hălē), Edmund or Edmond 1656-1742. English astronomer who applied Newton's laws of motion to predict correctly the period of a comet (1705).
- petrol
- petrolatum
- petroleum
- petroleum coke
- petroleum ether
- petroleum jelly
- petrolic
- petrologic
- petrological
- petrologically
- petrologist
- petrology
- Petronius
- "Petronius Arbiter."
- Petropavlovsk-Kamchatski
- Petropavlovsk-Kamchatskiy
- petrosal
- petrous
- Petrozavodsk
- Petrus
- Petrópolis
- PET scan
- PET scanner
- pet-sitter
- pet-sitting