STUDENTS [C] › a group of students who have lessons together: Katie and Sarah are in the same class at school. LESSON [C, U] › a period of time in which students are taught something: My first class starts at 8.30. He was told off for talking in class (= during the lesson). SOCIAL GROUP [C, U] › one of the groups in a society with the same social and economic position, or the system of dividing people into these groups: People are still very conscious of class in British society. She's from a working-class background. QUALITY [C] › a group into which people or things are put according to their quality: When it comes to mathematics, he's in a different class to his peers. second-class mail SIMILARITY [C] › a group of similar or related things, especially plants and animals