The term 'unlikely to fall over' can be summarized by the crossword solution 'STABLE, ' which is a six-letter word. STABLE is an adjective that describes something that is firmly fixed in place and not likely to move or fall over. It is often used to describe objects, such as furniture, that are unlikely to tip over or collapse. It can also be used to describe a person's emotional state, meaning that they are calm and not easily upset.