sierra, mountain, range of mountains; Sierra de Loja, prop. noun (a mountain range named after the town of Loja, in S. Spain).
siete, seven.
sietemesino (coll.), little dandy, fop; adj., immature.
siglo, century, age.
significación, f., significance.
significar, to signify, mean.
sigo, pr. ind. of seguir.
siguiente, following.
siguiera, siguiese, imp. subjs. of seguir.
silbar, to whistle.