'jargonistic' is formed in English by adding the suffix '-istic' (ultimately from Greek via Latin and French) to the noun 'jargon', producing an adjective meaning 'of or relating to jargon'.

'jargon' entered English from Old French 'jargon' meaning 'chatter' or 'twittering'; the adjective-forming suffix '-istic' came into English via French and Latin, and combining them yielded 'jargonistic' in modern English usage.

Originally, 'jargon' referred to chattering or unintelligible talk; over time it came to mean specialized terminology used within a particular field, and 'jargonistic' now means 'marked by such specialized terminology'.