From Longman Dictionary of Contemporary Englishpaydirtpay‧dirt /ˈpeɪdɜːt $ -dɜːrt/ noun [uncountable] → hit/strike paydirtFrom Longman Business Dictionarypaydirtpay‧dirt /ˈpeɪdɜːt-dɜːrt/ noun American English hit/strike paydirt informal to make a useful or valuable discovery that will make a lot of moneySYNstrike gold BrESales have been flat, and manufacturers can only hope they’ll strike paydirt with the new toy.