MURMUR' (4 letters) The crossword solutions for the term 'whisper loudly' are 'HISS' and 'MURMUR'. Hissing is a sound made by forcing air through a constricted opening, usually with the tongue. It is often used to express disapproval or displeasure. Murmuring is a low, continuous sound, like a quiet conversation. It is often used to describe a soft, indistinct sound, such as the sound of a gentle breeze or a whisper.