'nematocyst' originates from Greek, specifically the word 'nēma,' meaning 'thread,' and 'kystis,' meaning 'bladder.'

'nēma' and 'kystis' combined in Greek to form 'nematocystis,' which eventually became the modern English word 'nematocyst.'

Initially, it meant 'thread bladder,' referring to the structure's appearance, but over time it evolved into its current meaning of a stinging cell in coelenterates.