Encyclopedias, Almanacs, Transcripts, and Maps
- phosphor
- Phosphorus Removal
- Photic Zone
- Photios
- photocell
- Photochemical Reaction
- Photodegradable Plastic
- Photoperiod
- Photovoltaic Cell
- Phthalates
- Phthiraptera (Chewing and Sucking Lice)
- Phylactolaemata (Freshwater Bryozoans)
- Phyllocarida (Leptostracans)
- physical constants
- physical units
- Physics and Religion
- Physics of Water
- Phytoremediation
- Phytotoxicity
- Piciformes (Woodpeckers and Relatives)