From Longman Dictionary of Contemporary Englishsick noteˈsick note noun [countable] British English BECa note written by your doctor or your parents saying that you were too ill to go to work or school SYN excuse American English
Examples from the Corpus
sick note• You don't bring a proper sick note when you've been off school.From Longman Business Dictionarysick noteˈsick note noun [countable] British English a note written by your doctor saying that you are too ill to workEmployees must get a sick note from their doctor if they have been away from work for more than seven days. 