 ##  [pH](/ph) 

  ##  [pH](https://natural.quantumdictionary.io/ph-0) 

  
 [![Natural & Formal Sciences Dictionary](/sites/default/files/styles/large/public/2026-01/Natural%20%26%20Formal%20Sciences.png.webp?itok=2kCDRVQv)](/topic-specific-dictionaries/natural-formal-sciences)


**Natural &amp; Formal Sciences Dictionary**

 
Definition

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](https://health.quantumdictionary.io/ph-1) 

  
 [![Health & Life Sciences Dictionary](/sites/default/files/styles/large/public/2026-01/Health%20%26%20Life%20Sciences.png.webp?itok=yyyaiQOY)](/topic-specific-dictionaries/health-life-sciences)


**Health &amp; Life Sciences Dictionary**

 
Definition

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.