The term 'FIRST GEAR' is a phrase used to describe the lowest gear in a manual transmission vehicle. It is also known as 'LOW, ' which is a three letter word that can be used to solve a crossword puzzle. This gear is used when starting from a stationary position, such as at a stoplight or when parking, and is designed to provide the most torque for the engine. It is also used when driving on steep inclines or slippery surfaces.