thickenPronunciation: /ˈθɪk(ə)n/Translate thicken | into French | into German | into Italian | into Spanish Definition of thicken verb make or become thick or thicker: [with object]:thicken the sauce with flour [no object]:the fog had thickenedPhrases the plot thickens used when a situation is becoming more and more complicated and puzzling. thicken in other Oxford dictionaries Definition of thicken in the US English dictionary