adverb
in an inaudible or barely audible voice
made a snide remark to her sotto voce
Synonyms: faintly, mutedly, weakly
Related Word: low, quietly, softly; muffledly; mutteringly; aside, privately
Idioms: below one's breath, between one's teeth, in an aside, in an undertone, in a whisper, out of earshot, under one's breath
Contrasted words: aloud, out, out loud