'zealotry' originates from the Greek word 'ζηλωτής' (zēlōtēs), where 'ζηλοῦν' (zēloun) meant 'to be zealous or enthusiastic.'

'ζηλωτής' transformed into the Latin word 'zelotes,' and eventually became the modern English word 'zealot,' from which 'zealotry' is derived.

Initially, it meant 'enthusiastic pursuit,' but over time it evolved into its current meaning of 'excessive zeal or fanaticism.'