Entry 1 sense Webster, 1913 defenestration /(dē̇*fĕn`ĕs*trā"shŭn)/ · de·fen·es·tra·tion · IPA /diˌfɛnəˈstɹeɪʃən/ 01 n. the act of throwing (something or someone) out of a window. 1. the act of throwing (something or someone) out of a window.