"support for a railing," c.1600, from French balustre, from Italian balaustro "pillar," from balausta "flower of the wild pomegranate," from Greek balaustion (perhaps of Semitic origin, cf. Aramaic balatz "flower of the wild pomegranate"). Staircase uprights had lyre-like double curves, like the calyx tube of the pomegranate flower.