The term 'on all fours move' is referring to the crawling motion that many animals and young children use to move around. The crossword solution for this term is 'CRAWL, ' which is a five-letter word. Crawling is a form of locomotion in which an animal or person moves around on their hands and feet, with their belly close to the ground. It is a common form of movement for infants and young children, as well as some animals such as cats, dogs, and monkeys.