From Longman Dictionary of Contemporary EnglishA/S levelA/S level /ˌeɪ ˈes ˌlevəl/ noun [countable, uncountable] SES (Advanced Supplementary level) an examination that is taken by students in schools in England and Wales the year after they finish their GCSEs. Students usually continue with three or four of the same subjects after A/S level, in order to complete their A levelsdo/take A/S levelsA/S level in I’m taking A/S levels in French, Spanish, English, and Maths.