'hissy' originates from the English word 'hiss,' which is an onomatopoeic word imitating the sound of a hiss.

'hiss' was used in Middle English as 'hissen,' and eventually became the modern English word 'hiss.'

Initially, it meant 'to make a hissing sound,' but over time it evolved to describe a temperamental outburst as 'hissy fit.'