early 15c., "sweet, pleasing" (of an odor, a style of speaking or writing, etc.), from Late Latin mellifluus "flowing with (or as if with) honey," from Latin mel (genitive mellis) "honey" (related to Greek meli "honey;" see Melissa) + -fluus "flowing," from fluere "to flow" (see fluent). Related: Melifluously; melifluousness.