Entry 3 senses · 2 variants Webster, 1913 Thirteen /(thẽr"tēn`)/ · Thir·teen · IPA /ˌθɝtˈtin/ a. n. 01 a. One more than twelve; ten and three; as, thirteen ounces or pounds. 1. One more than twelve; ten and three; as, thirteen ounces or pounds. 02 n. The number greater by one than twelve; the sum of ten and three; thirteen units or objects. 1. The number greater by one than twelve; the sum of ten and three; thirteen units or objects. 2. A symbol representing thirteen units, as 13 or xiii.