The crossword solution for the term STOP SYMBOL is RED, which is a three-letter word. RED is often used as a stop symbol in many contexts, such as traffic lights, warning signs, and other forms of communication. It is also used to indicate danger or caution, and can be seen in many places, from road signs to emergency exits. RED is also used to signify the end of a process or activity, such as the end of a movie or a game.