The sign "NO" can use either a polite double motion or a more firm or definite single motion. It is also directional in nature--meaning, if I hold my hand off to my right and I point the palm toward myself while doing the sign, it can mean "He told me no." Also see: YES
A firm, solid "no" as in a command. Uses one motion.
Another variation of no uses a double motion and a negative headshake.
