Middle English soun, from Anglo-Norman French soun (noun), suner (verb), from Latin sonus . The form with -d was established in the 16th cent.
Sonus is a Latin word, derived from the Greek “tonos” that means “noise, sound” or “tone, character, style.” It is also the root word for sonic and sound.
sona (“prosperous, fortunate, lucky”) + -us
good fortune, prosperity, happiness