pH

This term functions as a technical measurement of chemical acidity or alkalinity. It is used predominantly in scientific, medical, and agricultural contexts to describe the state of a solution, where a value of 7 is neutral, lower values are acidic, and higher values are basic.

Grammatically, pH is treated as an uncountable noun because it refers to a scale or a specific measurement value rather than a discrete object. It does not have a plural form; one does not refer to multiple pHs, but rather to different pH levels or pH values.