Stumble (over) is a term used to describe an action of tripping or losing balance due to an obstacle. The crossword solutions for this term are TRIP (4 letters) and TRIPON (6 letters). TRIP is a verb that means to move or cause to move with a sudden jerky motion, while TRIPON is a verb that means to stumble or TRIP over something. Both words can be used to describe the same action of tripping or losing balance due to an obstacle.