means To make a sharp, sustained sibilant sound, like an 's' drawn out — whether from a snake, an angry cat, escaping steam, or a disapproving crowd.

from A word born of pure imitation: 'hiss' simply mimics the sound it names, an echoic coinage found in Middle English as 'hissen.' Such words — where the noise makes the word — are called onomatopoeic, and 'hiss' is a textbook case, the mouth shaping the very thing it describes. Cousins in feeling, if not in strict descent, include 'buzz,' 'fizz,' and 'whisper,' all built from the soft friction of breath.