The term 'humdrum routine' can be summed up by two crossword solutions: GRIND (5 letters) and RUT (3 letters). GRIND is a verb meaning to work hard and laboriously, often in a tedious or monotonous way. RUT is a noun meaning a habit or pattern of behavior that has become dull and unproductive. Together, these words describe a situation where someone is stuck in a dull, repetitive cycle of work with no progress or excitement.