The term CAL COLUMN is a reference to the days of the week. The acronym CAL stands for 'CALENDAR' and the column refers to the days of the week. The solutions for the crossword are MON (3 letters), SAT (3 letters), FRI (3 letters), THU (3 letters), TUE (3 letters), TUES (4 letters), and THURS (5 letters). These solutions refer to Monday, Saturday, Friday, Thursday, Tuesday, and Thursdays respectively. These days of the week are commonly used to refer to the days of the week in many cultures and languages.