pH

Natural & Formal Sciences Dictionary
Negative base-10 logarithm of the hydrogen ion activity in an aqueous solution; a dimensionless scalar used to express acidity or basicity on a compact numeric scale.

pH

Health & Life Sciences Dictionary
The negative base‑10 logarithm of the hydrogen ion activity in an aqueous food matrix, used as a measure of acidity or alkalinity that influences chemical reactions, enzyme activity, and the growth of many microorganisms in food systems.