To make a noise like a long s sound. (Cambridge Dictionary)
To say something in a quiet angry way. (Cambridge Dictionary)
To make a sharp sibilant sound. (Merriam – Webster)
Make a sharp sibilant sound as of the letter s. (Oxford Dictionaries)
(of a person) make a sibilant sound as a sign of disapproval or derision. (Oxford Dictionaries)
To hiss means to make a sound like a long ‘s’. (Collins Dictionary)
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