The story
Latin: argūmentum (“argument”, “proof”) + ad (“to”, “toward”) + passiōnēs (accusative plural of passio, “suffering”, “passion”) ≈ “appeal to the passions”
Etymology from Wiktionary, CC BY-SA 4.0.
argumentum ad passiones
Today it means: An appeal or argument intended to convince the listener(s) by agitating the emotions, rather than by appealing to sober judgment. Full definition →