probiotic UK /ˌpɹəʊ.baɪˈɒt.ɪk/US /ˌpɹoʊ.baɪˈɑ.tɪk/adjective 2noun 1forms 3 adjective2 •Describing any dietary supplement that contains live bacteria for therapeutic purposes. •Of, or relating to probiosis; ecologic facilitation. noun1 •A food or dietary supplement, such as a yogurt, containing live bacteria for therapeutic reasons. formsprobiotics · more probiotic · most probiotic