Word parts im- + mature Pronunciation IPA (key): /ɪməˈtjʊə(r)/ or /ɪməˈtʃʊə(r)/ or /ɪməˈtʃə(r)/ Audio (UK)(file) Adjective Positive immature Comparative more immature Superlative most immature If something is immature, it has not fully developed. If a person is immature, they have a childish behavior. The man was immature for throwing a tantrum.Wikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads