pH

noun \ˈpē-ˈāch\

: a number between 0 and 14 that indicates if a chemical is an acid or a base

Full Definition of PH

: a measure of acidity and alkalinity of a solution that is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity and on which each unit of change represents a tenfold change in acidity or alkalinity and that is the negative logarithm of the effective hydrogen-ion concentration or hydrogen-ion activity in gram equivalents per liter of the solution; also : the condition represented by a pH number

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Origin of PH

German, from Potenz power + H (symbol for hydrogen)

First Known Use: 1909

PH

abbreviation

Definition of PH

pinch hit

public health

Purple Heart

See PH defined for English-language learners

PH Defined for Kids

pH

noun \ˈpē-ˈāch\

Definition of PH for Kids

: a measure of the acidity or alkalinity of a substance <Lemon juice has a pH of about 2.5.> <Water has a pH of 7.>

Medical Dictionary

pH

noun \(ˈ)pē-ˈāch\

Medical Definition of PH

: a measure of acidity and alkalinity of a solution that is a number on a scale on which a value of 7 represents neutrality and lower numbers indicate increasing acidity and higher numbers increasing alkalinity and on which each unit of change represents a tenfold change in acidity or alkalinity and that is the negative logarithm of the effective hydrogen-ion concentration or hydrogen-ion activity in gram equivalents per liter of the solution <instead of saying that the concentration of hydrogen ion in pure water is 1.00 x 10⁻⁷, it is customary to say that the pH of pure water is 7—Linus Pauling>; also : the condition represented by such a number—compare pk