Where It Comes From
Mellifluous comes from Late Latin mellifluus, a direct combination of mel ("honey") and fluere ("to flow") — literally "flowing with honey." The word entered English in the early 1400s, originally describing writing and speech that flowed as smoothly and sweetly as honey.
Six centuries later, it's still almost exclusively reserved for the way something sounds.
Say It Around the World
Spanish's "melifluo" is a direct cognate, confirmed by the Real Academia Española. French doesn't have a honey-based cognate, so it reaches for "mélodieux" instead. German's "wohlklingend" is a completely native compound — literally "well-sounding" — built without any Latin honey reference at all.
The next word is mellifluous's exact opposite — the sound of a toddler, a blender, and a smoke alarm all going off at once.