símbolo, m., symbol.
simple, foolish, crazy; subst. m., simpleton, fool.
simplemente, simply.
simplificar, to simplify.
sin, without; — duda, doubtless; — ejemplar, unprecedented; — embargo, however, nevertheless, notwithstanding; — que, without.
singular, singular, strange.
sinnúmero, m., infinite number.
sino, but (after a negative); but rather; if not, except; no tan sólo, — que, not only, but also; — que, but, but rather, except that.
sinuosidad, f., turn, bend, winding, sinuosity, curve.
siquiera, even, at least, unless, even though; ni oyó —, he did not even hear; ni tan —, not even, not so much as.