im·mis·sion \(ˈ)i|mishən\noun Etymology: Latin immission-, immissio, from immissus past participle of immittere to send in (from in- in- (II) + mittere to send) + -ion-, -io -ion — more at smite 1. a.archaic: an act of sending or letting in : injection, admission, introduction b.obsolete: something introduced 2.: commixture 2