A "sick day" is a term we all know too well. It refers to a day off work or school when someone isn't feeling well. However, there are some other synonyms that can be used instead of "sick day". For instance, "sick leave" is a more official term used in workplaces to refer to days off taken due to illness. "Medical leave" is another synonym, typically used in more formal settings to refer to a longer period of time off work due to an illness or injury. Finally, "absent due to illness" or "out sick" are commonly used phrases to indicate an individual's absence due to illness. These are a few alternatives to the well-known term "sick day".