pH Definition

pH
pH value
noun

1. chem.
A measure of the relative acidity or alkalinity of a solution expressed as the logarithm of the reciprocal of the hydrogen-ion concentration of the solution.

Etymology: Early 20c: a shortening of German Potenz power or exponent + H, the symbol for hydrogen.

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Purple Heart
noun

1. military.
In the USA: a medal awarded for wounds received on active service.

Etymology: 1932 in present form.