Quiz: Remember the definition of mal de mer?
1650s, from French limpidité or directly from Late Latin limpiditatem (nominative limpiditas) "clarity," from Latin limpidus (see limpid).
c.1600, from French limpide (15c.) and directly from Latin limpidus "clear," from limpa "water goddess, water;" probably cognate with lympha "clear liquid" (see lymph). Related: Limpidly.