PH, ph, pH, and Ph are initialisms or other abbreviations that may refer to:
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[edit] Sciences
- pH, a measure of acidity in chemistry
- picohenry, an SI Unit of electrical inductance
- PH (complexity), the union of all complexity classes in the polynomial hierarchy in computational complexity theory
- -Ph, a phenyl ring in organic chemistry
- ph or phot, a measurement of illuminance (photometry)
- Pleckstrin homology domain, a part of many proteins which bind phosphoinositides with high affinity
- Pulmonary hypertension, a medical condition
- Ph (digraph), a common digraph that represents the phoneme /f/ (voiceless labiodental fricative) in phonetics
- Pyramid Head, an enemy in the Silent Hill series
- Ph is an old name service protocol described by RFC 2378
- Pizza Hut
- Planet Hope
- PH, the Philippines' ISO country code
- .ph, the Philippines' Internet country code top-level domain
- PH (Papa, Hotel), Aircraft Registration prefix for The Netherlands
- phi (letter), the Greek letter (φ)
- Polynesian Airlines' IATA airline designator
- Ph.D, Philosophiæ Doctor (Latin)
- Colégio pH, a Brazilian school in Rio de Janeiro, RJ
- Poul Henningsen Danish writer and designer.
- Paul Harris school, Venezuelan bilingual school in Caracas
- PH connector, a connector between cables and printed circuit boards
- Partido Humanista, "Humanist Party" in Spanish