Entry 2 senses · 2 variants Webster, 1913 Surtax /sẽrt'-ăksˌ/ · Sur·tax · IPA /ˈsɝː.tæks/ n. v. t. 01 n. An additional or extra tax. 1. An additional or extra tax. 02 v. t. To impose an additional tax on. 1. To impose an additional tax on.