thirty
n.n. the number that comes after twenty-nine and before thirty-one. It is written as the number 30.
n. the cardinal number equivalent to the product of ten and three. Functions as a determiner when preceding a noun or as a noun when referring to the digit or the set itself.
There are thirty days in the month of June.
The teacher asked the students to count to thirty before they started the game.
The historical archive contains thirty distinct volumes, each documenting a different decade of the city's architectural evolution since the late nineteenth century.
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”).
When used as a noun, it is countable; when used as a determiner, it precedes the plural noun it modifies.
threetythirtyLearners sometimes mistakenly follow the pattern of 'fourty' or 'sixty' by adding '-ty' to 'three' instead of using the irregular form 'thirty'.