Thirty

How to spell thirty

6 letters · 2 syllables

How to pronounce thirty

Say the part in capitals loudest.

What does thirty mean?

1. otherThe cardinal number equal to three times ten; 30.

Thirty in a sentence

• The train leaves at thirty minutes past the hour.

• She turned thirty at a quiet dinner with her family.

Where does thirty come from?

Language of origin: Germanic

Thirty comes from the Old English þrītig, which simply combined the word for three with the suffix -tig meaning 'a group of ten', so it literally meant 'three tens'. The same Germanic -tig element survives in all the modern tens words such as forty, fifty and sixty, and it is a distant cousin of the standalone word 'ten' itself. The shift in the vowel and the appearance of the letters 'ir' reflect the way three (þrēo) was reshaped when it took the suffix; English kept the spelling 'thir-' here even though we say 'three' with a clear long vowel. The word has been part of everyday English since before the Norman Conquest and has never been borrowed from another language. The small spelling trap is precisely that 'thirty' does not look like 'three': writers reaching for the number sometimes hesitate over the 'ir' and the single 't'.

How the word is built

• thir- (variant of three, from Old English þrēo)
• -ty (tens suffix, from Old English -tig 'group of ten')