The term 'CHECK UP ON' can be broken down into three crossword solutions: QUIZ (4 letters), LOOKIN (6 letters), and SEEAFTER (8 letters). QUIZ is a verb meaning to ask questions in order to test knowledge or obtain information. LOOKIN is a verb meaning to search for something, often by looking around. SEEAFTER is a verb meaning to observe or take care of something. Together, these three words suggest the idea of examining something closely in order to gain knowledge or understanding.