Entry 1 sense Webster, 1913 Illuminating /ĭlˌ-o͞om'-ən-ātˌ-ĭng/ · Il·lu·mi·na·ting · IPA /ɪlˈluməneɪtɪŋ/ 01 a. Giving or producing light; used for illumination. 1. Giving or producing light; used for illumination. Phrases & compounds Illuminating gas — See Gas, n., 2 (a).