pH

1 of 2

noun

ˈpē-ˈāch 

: 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

PH

2 of 2

abbreviation

1

pinch hit

2

public health

3

Purple Heart

Examples of pH in a Sentence

Recent Examples on the Web

Noun

Lower Soil pH Wood ash has a high pH, usually around 10 to 12, says Chelsea McKinley, plant health specialist at the U.S. Botanic Garden in Washington, D.C. —Leanne Potts, Better Homes & Gardens, 17 Sep. 2024

This is because lower gastric pH facilitates better iron absorption. —Stephen C. George, Discover Magazine, 12 Feb. 2024

Then several sample portions are measured for nutrient content, pH and organic matter. —Lauren David, Washington Post, 13 Nov. 2023

Soil pH is defined as the acidity or alkalinity of the soil. —Rita Perwich, San Diego Union-Tribune, 4 Nov. 2023

Word History

Etymology

Noun

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

First Known Use

Noun

1909, in the meaning defined above

Phrases Containing pH

• pH meter

Kids Definition

pH

noun

(ˈ)pē-ˈāch 

: a number used in expressing acidity or alkalinity on a scale whose values run from 0 to 14 with 7 representing neutrality, numbers less than 7 increasing acidity, and numbers greater than 7 increasing alkalinity

also : the condition represented by such a number

Medical Definition

ph

1 of 2 abbreviation

1

pharmacopoeia

2

phosphor

3

phot

pH

2 of 2 noun

(ˈ)pē-ˈāch 

: 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