The term 'REDUCE SPEED' can be expressed in several ways, including the five-letter word 'BRAKE, ' the four-letter word 'SLOW, ' the three-letter word 'SLO, ' and the six-letter word 'SLOWUP.' Braking is a common way to reduce speed, as it applies pressure to the wheels of a vehicle, causing them to SLOW down. The word 'SLOW' is an adjective that describes something that moves at a low speed. The word 'SLO' is an abbreviation of the phrase 'SLOW down, ' which is another way to express the idea of reducing speed. Finally, the word 'SLOWUP' is a noun that refers to a situation in which traffic slows down or stops.