sill, n. [threshold]; window [sill].
silliness, n. [folly], [foolishness], puerility, stupidity, inanity, inaneness, [absurdity], [senselessness], ineptitude.
silly, a. witless, [foolish], [simple], fatuous, [imbecile], [half-witted]; [stupid], [unwise], inept, [absurd], inane, [nonsensical], [senseless], [puerile].
silver, n. argentum; bullion (uncoined silver). Associated words: filigree, platinum, desilverize, desilverization, patio, vermeil, fulguration, silversmith.
silvery, a. [silver], argent, argentine, argentous, argentiferous.
similar, a. [like], corresponding, resembling, homogeneous, analogous.
similarity, n. [analogy], homogeneity, [likeness], similitude, [correspondence].
simile, n. [comparison], [metaphor].
simoon, n. [desert wind], khamsin, samiel.
simper, n. [smirk].