I give up, you're right.
'Arrendo' — ar-REN-do. From 'arrendersi' (to surrender). Stress on the second syllable. Double 'r' is rolled.
Use when conceding defeat in a discussion — often with a mix of exasperation and good humour. The military metaphor ('surrender') makes it playful even in concession.
'Arrendersi' (to surrender) is borrowed from military vocabulary. 'Mi arrendo' (I surrender) in a debate context means you've been defeated by better arguments. It's often said with a laugh — accepting defeat while maintaining dignity.
Hai vinto.
You've won.
Direct acknowledgement of defeat — short, sporting, magnanimous
Non ho più argomenti.
I have no more arguments.
Explains why you're conceding — you've run out of counterarguments
Mi hai messo all'angolo.
You've put me in a corner.
Idiomatic — 'mettere all'angolo' (to put in the corner) = to corner someone in a debate
The generous response to someone conceding in Italian culture is often to share in their experience — 'anch'io non lo sapevo' (I didn't know it either) — which preserves their dignity. Gloating over a won argument is considered poor sportsmanship ('scarsa sportività').