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 study authors also found that the ratio of gaseous carbon dioxide to ice differs significantly from what is seen in star-forming regions, indicating that the processes controlling ice formation or alteration in planetary nebulae may be very different. —Rupendra Brahambhatt, Interesting Engineering, 15 Mar. 2026

For the spring, throwing fastballs at 96 mph, Curvelo has a 10-to-0 strikeout-to-walk ratio. —Evan Grant, Dallas Morning News, 15 Mar. 2026

The ratio of dollars per pupil may look shocking for Cardiff and Rancho Santa Fe (at $404/pupil in Cardiff and $489/pupil in RSF). —Marsha Sutton, San Diego Union-Tribune, 15 Mar. 2026

The service Always friendly, and a good guest-to-staff ratio means help is never far away. —Condé Nast, Condé Nast Traveler, 14 Mar. 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