Entry 5 senses · 2 variants Webster, 1913 Sizing · Siz·ing · IPA /ˈsaɪzɪŋ/ n. n. 01 n. Act of covering or treating with size. 1. Act of covering or treating with size. 2. A weak glue used in various trades; size. 02 n. The act of sorting with respect to size. 1. The act of sorting with respect to size. 2. The act of bringing anything to a certain size. 3. Food and drink ordered from the buttery by a student.(Univ. of Cambridge, Eng.)