ratio

noun

ra·​tio ˈrā-shē-ˌō 

-(ˌ)shō

plural ratios

1

a

: the indicated quotient of two mathematical expressions

b

: the relationship in quantity, amount, or size between two or more things : proportion

2

: the expression of the relative values of gold and silver as determined by a country's currency laws

Synonyms of ratio

• rate

Examples of ratio in a Sentence

What is the length-to-width ratio?

the ratio of students to teachers in the school is nine to one

Recent Examples on the Web

The preliminary Bureau of Labor Statistics data for June shows the teen employment-to-population ratio at a nine-month low and the unemployment rate trending higher than a year ago. — Alicia Wallace, CNN Money, 7 Aug. 2026

Of course, earnings are crucial and form the basis of the most common way to value stocks on Wall Street ( a price-to-earnings ratio ). — Zev Fima, CNBC, 6 Aug. 2026

The industry and its analysts would prefer medical benefit ratios to be below 90% and into the mid 80s, so Oscar has achieved that measure for the time being. — Bruce Japsen, Forbes.com, 6 Aug. 2026

Using a water-soluble fertilizer with an NPK ratio of 15-30-15 will give the plants a boost of the phosphorus needed to help your flowers start producing buds and blossoms again. — Mary Marlowe Leverette, Southern Living, 6 Aug. 2026

Word History

Etymology

Latin, computation, reason — more at reason entry 1

First Known Use

1660, in the meaning defined at sense 1a

Phrases Containing ratio

• aspect ratio
• case fatality ratio
• common ratio
• focal ratio
• golden ratio
• gyromagnetic ratio
• loss ratio
• nutritive ratio
• Poisson's ratio
• price-earnings ratio
• ultima ratio

Rhymes for ratio

• acknow
• aglow
• ago
• airglow
• aloe
• altho
• although
• ammo
• backflow
• backhoe
• banjo
• barbeau

Kids Definition

ratio

noun

ra·​tio ˈrā-shō 

-shē-ˌō

plural ratios

1

: the quotient of two numbers or mathematical expressions

the ratio of 6 to 3 may be expressed as 6:3, ⁶⁄₃, and 2

2

: the relationship in quantity, amount, or size between two or more things

women outnumbered men in the ratio of three to one

Medical Definition

ratio

noun

ra·​tio ˈrā-(ˌ)shō, -shē-ˌō 

plural ratios

: the relationship in quantity, amount, or size between two or more things see sex ratio