probioticpro‧bi‧ot‧ic /ˌprəʊbaɪˈɒtɪk◂ $ ˌproʊbaɪˈɑː-/ noun [countable, uncountable]a food or other substance that contains bacteria and is used in a positive way to improve health, or the use of this type of food to improve health: Probiotics have been reported to enhance digestion. probiotic yoghurt