Entry 4 senses · 2 variants Webster, 1913 Centenary /sĕn'-tən-ĕrˌ-ē/ · Cen·te·na·ry · IPA /sɛnˈtɛnəɹi/ a. n. 01 a. Relating to, or consisting of, a hundred. 1. Relating to, or consisting of, a hundred. 2. Occurring once in every hundred years; centennial. 02 n. The aggregate of a hundred single things; specifically, a century. pl. Centenaries 1. The aggregate of a hundred single things; specifically, a century. 2. A commemoration or celebration of an event which occurred a hundred years before.