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

• 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

Greece, which saw its debt ratio balloon above 200% during the COVID-19 crisis, has cut it almost in half through spending restraint and tax reforms. —Eva Roytburg, Fortune, 28 Oct. 2025

The panels are made from a proprietary polymer composite with an undisclosed fiber-to-resin ratio. —Kaif Shaikh, Interesting Engineering, 27 Oct. 2025

Alternatively, the ratio could reflect a fundamental constraint on heat exchange. —Quanta Magazine, 27 Oct. 2025

The king would melt bars of chocolate with water in a 1-to-1 ratio, then thicken the mixture gently over low heat, slowly whisking in an egg yolk to give the drink a smooth richness. —Aleksandra Crapanzano, The Atlantic, 27 Oct. 2025

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