Stagnate is a verb which means to remain in the same state or condition without progress or development. It is often used to describe a situation where something has stopped moving forward or has become stagnant. The crossword solution for the term 'stagnate' is 'IDLE, ' which means to be inactive or not doing anything. This is an apt description of the state of stagnation, as it implies that nothing is happening and no progress is being made.