# thirty

> English word · Numeral · IPA /ˈθɜːti/ · frequency rank #3,791

## Definitions
1. The cardinal number occurring after twenty-nine and before thirty-one, represented in Arabic numerals as 30.

## Etymology
From Middle English thirty, metathetic alternant of Middle English thriti, þrittiȝ, from Old English þrītiġ (“thirty”), from Proto-Germanic *þrīz tigiwiz (“thirty”, literally “three tens”), equivalent to three + -ty. Cognate with Scots therty, tretty (“thirty”), West Frisian tritich (“thirty”), Dutch dertig (“thirty”), German dreißig (“thirty”).

## Easily confused with
- **titty** (https://plainspell.com/en/vs/thirty-vs-titty)
- **thorny** (https://plainspell.com/en/vs/thirty-vs-thorny)
- **twisty** (https://plainspell.com/en/vs/thirty-vs-twisty)
- **thrifty** (https://plainspell.com/en/vs/thirty-vs-thrifty)
- **third** (https://plainspell.com/en/vs/third-vs-thirty)
- **thirds** (https://plainspell.com/en/vs/thirds-vs-thirty)
- **thirst** (https://plainspell.com/en/vs/thirst-vs-thirty)
- **thinly** (https://plainspell.com/en/vs/thinly-vs-thirty)
- **thingy** (https://plainspell.com/en/vs/thingy-vs-thirty)
- **thirsty** (https://plainspell.com/en/vs/thirsty-vs-thirty)
- **thirdly** (https://plainspell.com/en/vs/thirdly-vs-thirty)

## Common misspellings (10)
`htirty`, `thhirty`, `thirrty`, `thirtty`, `thirtyy`, `thiryt`, `thitry`, `thrity`, `tihrty`, `tthirty`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/thirty