Al·too·na 
(ăl-tnə)
(ăl-tnə) A city of central Pennsylvania on the eastern slopes of the Allegheny Mountains east of Pittsburgh. It was laid out in 1849 by the Pennsylvania Railroad as a switching point for locomotives used to cross the mountains.
- petrogenetic
- petroglyph
- petroglyphic
- Petrograd
- petrographer
- petrographic
- petrographical
- petrographically
- petrography
- petrol
- petrolatum
- petroleum
- petroleum coke
- petroleum ether
- petroleum jelly
- petrolic
- petrologic
- petrological
- petrologically
- petrologist
- petrology
- Petronius
- "Petronius Arbiter."
- Petropavlovsk-Kamchatski
- Petropavlovsk-Kamchatskiy