S! What begins with the letter 'S'? Something that begins with the letter 'S'... hmm... let's see. There is street, somersault, spa, sauce, soy sauce, sneeze, shake, salute, and sun! "Salute the sun!" as Male and Female Trainer from Super Smash Bros. would say; though they don't really salute it, they just give their salutations. It's a yoga exercise.