Where does “thirty” come from?

thirty (Middle English) comes from Old English þritig, from Old English þrī, from Proto-West Germanic þrīʀ, from Proto-Germanic þrīz, from Proto-Indo-European *tréyes.

Ancestry of “thirty”, step by step

StepLanguageWordMeaning
1Old Englishþritigthirty
2Old Englishþrīthree
3Proto-West Germanicþrīʀthree
4Proto-Germanicþrīzthree
5Proto-Indo-European*tréyes—

Words derived from “thirty”

Every word from Proto-Indo-European *tréyes →Every word from Proto-Germanic þrīz →Every word from Proto-West Germanic þrīʀ →