The story
- Proto-Indo-European*h₂erǵ-
- Proto-Indo-European*h₂érǵus
- Proto-Italic*argusder.?
- Latinarguō
- Latinargūmentum
- Latinargūmentor
- Medieval Latinargūmentātīvus
- Middle Englishargumentatif
- English todayargumentative
From Late Middle English argumentatif (“syllogistic, sophistic”), from Old French argumentatif, argumentative (modern French argumentatif (“argumentative”)) and Medieval Latin, Late Latin argūmentātīvus, from Latin argūmentātor + -īvus (suffix forming adjectives).
Etymology from Wiktionary, CC BY-SA 4.0.