The term MO is represented by two crossword solutions, ONCE and SEVENTH. MO is an abbreviation for the Latin phrase 'modo et modo', which translates to 'now and then' or 'SOMETIMES'. This phrase is often used to describe something that happens occasionally or irregularly. The two crossword solutions, ONCE and SEVENTH, are both related to this concept of irregularity. ONCE implies that something happens only ONCE, while SEVENTH implies that something happens every seventh time. Together, these two solutions represent the idea of something happening irregularly or occasionally.