[ve.lum] n, pl ve.la [NL, fr. L, curtain] (1753) 1: a membrane or membranous part resembling a veil or curtain: as a: soft palate b: an annular membrane projecting inward from the margin of the umbrella in some jellyfishes (as the hydromedusans)
2: a swimming organ that is esp. well developed in the later larval stages of many marine gastropods