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• ph
  ph

  phot; phots.
• pH
  pH

  the symbol for the logarithm of the reciprocal of hydrogen ion concentration in gram atoms per liter, used to express the acidity or alkalinity of a solution on a scale of 0 to 14, where less than 7 represents acidity, 7 neutrality, and more than 7 alkalinity.
• Ph
  Ph

  abbreviation

  phenyl.
• ph.
  ph.

  abbreviation

  phase.
• P.H.
  P.H.

  abbreviation

  Public Health.

ph

¹ American  

Optics.

1. phot; phots.

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pH ² American  

Chemistry.

1. the symbol for the logarithm of the reciprocal of hydrogen ion concentration in gram atoms per liter, used to express the acidity or alkalinity of a solution on a scale of 0 to 14, where less than 7 represents acidity, 7 neutrality, and more than 7 alkalinity.

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Ph ³ American  

abbreviation

Chemistry.

1. phenyl.

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ph. ⁴ American  

abbreviation

1. phase.

2. phone.

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P.H. ⁵ American  

abbreviation

1. Public Health.

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ph ¹ British  

abbreviation

1. Philippines

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pH ² British  

noun

1. potential of hydrogen; a measure of the acidity or alkalinity of a solution equal to the common logarithm of the reciprocal of the concentration of hydrogen ions in moles per cubic decimetre of solution. Pure water has a pH of 7, acid solutions have a pH less than 7, and alkaline solutions a pH greater than 7

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ph. ³ British  

abbreviation

1. phase

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Ph ⁴ British  

symbol

1. phenyl group or radical

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pH Scientific  

/ pē′āch′ /

1. A numerical measure of the acidity or alkalinity of a solution, usually measured on a scale of 0 to 14. Neutral solutions (such as pure water) have a pH of 7, acidic solutions have a pH lower than 7, and alkaline solutions have a pH higher than 7. The pH of lemon juice is 2.4; that of household ammonia is 11.5. The normal pH for human blood is 7.4.

2. ◆ The letters pH stand for potential of hydrogen, since pH is effectively a measure of the concentration of hydrogen ions (that is, protons) in a substance. The pH scale was devised in 1923 by Danish biochemist Søren Peter Lauritz Sørensen (1868–1969).

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pH Cultural  

1. In chemistry, a measure of the strength of an acid or a base. A neutral solution has a pH of 7; acids a pH between 0 and 7; bases a pH from 7 to 14. Specially treated strips of paper (see litmus), or more precise instruments, may be used to measure pH.

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Example Sentences

Companies have scoured the globe in search of raw materials to create a natural blue food color that can withstand changes to heat, light and pH.

From The Wall Street Journal • Jun. 18, 2026

They measured temperature, pH and salinity and exposed natterjack spawn to water from each of the sites.

From BBC • May 31, 2026

People have been urged to stay away from a flooded quarry where the water has a pH level "comparable to bleach", following a surge in visitors over the bank holiday weekend.

From BBC • May 28, 2026

By understanding how bacterial metabolism drives this type of motion, scientists may be able to slow or stop it by altering environmental conditions such as pH or sugar levels.

From Science Daily • Mar. 13, 2026

At dinner I share the good news: "I tested the soil. And it is neutral. The pH is a perfect 7."

From "Counting by 7s" by Holly Goldberg Sloan