Real Dictionary

mark down
to make a note of; write down; record
to reduce the price of
phrasal verb: If a teacher marks a student down, the teacher puts a lower grade on the student's work because of a mistake that has been made.
phrasal verb: If you mark someone down as a particular type of person, especially a type that you do not like, you consider that they have the qualities which make them that type of person.
phrasal verb: If you mark something down, you write it down.
phrasal verb: To mark an item down or mark its price down means to reduce its price.
verb: If you mark down something that you are selling, you reduce the selling price.