thirty UK /ˈθɜːti/US /ˈθɝti/number 1noun 2forms 2phrases 1 number1 •the number 30To conclude, here in tabular form is a summary of our ratings of espressos produced from thirty pod, capsule and disc blends. — 2009 noun2 •A commercial lasting 30 seconds. •(slang) A rack of thirty beers. formsthirties · thirty-somethings Phrases with thirty oh dark thirtySome unspecified hour in the early morning (implying an unpleasant time to be awake).