Pronunciation (US) IPA (key): /ˈɑptɪməm/ (UK) IPA (key): /ˈɒptɪməm/ Audio (UK)(file) Noun Singular optimum Plural optimums or optima If something is at optimum condition, it is at the most favorable situation. Related words optimalWikiwand - on Seamless Wikipedia browsing. On steroids.Remove ads