means Resembling silver in color or sheen, or having a clear, light, ringing quality of sound.

from Built from "silver" plus the homely English suffix "-y," which turns nouns into "having the quality of" (think watery, glassy, frosty). "Silver" itself is old Germanic stock — Old English "seolfor," kin to Dutch "zilver" and German "Silber" — and its deeper roots are murky enough that scholars suspect it was borrowed into early Germanic and Balto-Slavic from some unknown, possibly Near Eastern, source. The sound sense (a "silvery" voice or laugh) leans on the old idea that struck silver rings out bright and pure.