sotto voce

(sŏtˈō vōˈchē, sōtˈtō vōˈchĕ)

1. In soft tones, so as not to be overheard; in an undertone: “There were aspersions cast, sotto voce, but knees quickly folded into curtsies when introductions were in order” (Barbara Lazear Ascher).
2. Music In very soft tones. Used chiefly as a direction.