SIGMUND: Old German for "victorious protector." Don't overanaylze your ultimate choice for a name. Go with one you like. Relatives: Siegmund, Sigismond, Sigismundo, Siegfried, Sigfrid, Siffre, Sigvard, Siggy, Ziggy. Namesakes: Sigmund Freud, Siegfried Sassoon, "Ziggy Stardust."
SIGRID: Old Norse for "winning adviser." Relatives: Sigrath, Sigwald, Sigurd.
SILAS: From the Latin for "wood." Put Silas on the birth certificate and call him Woody. Namesake: Silas Marner.
SIMON: From the Hebrew for "listener." Simon says consider Simon. Relatives: Simeon, Siomonn, Sim, Shimon. Namesakes: Saint Simeon, Simon Bolivar, Paul Simon, Shimon Perez, "Simon Legree."
SIMONE: From the Hebrew for "listener." Long popular in France, this pretty name could withstand more usage. Relatives: Simona, Simonette. Namesakes: Simone Signoret, Simone de Beauvoir.
SINCLAIR: A French contraction of Saint Clair. There are several contractions akin to Sinclair (such as Sinjon for St. John). Sinclair would work well for a girl, too. Namesakes: Sinclair Lewis, Upton Sinclair.
SKEET: Middle English for "speedy." Skeets are also the clay "birds" used in target shooting. Relatives: Skeets, Skeat, Skeeter. Namesake: Skeeter Davis.
SKIPP: Old Norse for "ship owner." Skip is often used as a nickname in lieu of a more formal given name. It also stands well alone and proves convenient if you own a boat or a kangaroo. Relatives: Skipper, Skippy, Skip.
SLOAN: Irish Gaelic for "warrior." Has a distinctive pedigreed ring to it. Relative: Sloane. Namesakes: Sloan Wilson, John French Sloan.