Odysseus deceives the Cyclops by tricking him. He tells the Cyclops that his name is "Noman" thus when Odysseus defeats the Cyclops, and the Cyclops runs to his friends (other Cyclopes) for help and declares the name of the offender, then the Cyclops would have states that "Noman" or rather "no - man" had hurt him. Therefore his friends would think that no one had hurt him and hence, not help him.
