Entry 1 sense Webster, 1913 Investigator /ĭnˌ-vĕs'-təg-ātˌ-ẽr/ · In·ves·ti·ga·tor · IPA /ɪnˈvɛs.tɪˌɡeɪ.tɚ/ 01 n. One who searches diligently into a subject. 1. One who searches diligently into a subject.