means A device that converts an electrical signal into sound loud enough to fill a room, hall, or street.

from A plain English compound of "loud" and "speaker," coined in the early days of electrical sound reproduction (around the turn of the 20th century) — "speaker" because it spoke, "loud" because that was the whole point. "Loud" itself traces back to Old English "hlud" and a Germanic root, a distant cousin of words in Latin and Greek for "hearing" and "glory" — the same ancient family that gave us "listen."