Entry 1 sense Webster, 1913 Fireproofing /fī'-ẽrp-ro͞ofˌ-ĭng/ · Fire·proof·ing · IPA /fˈaɪərprˌuːfɪŋ/ 01 n. The act or process of rendering anything incombustible; also, the materials used in the process. 1. The act or process of rendering anything incombustible; also, the materials used in the process.