verb/de.ʁɛ.zɔ.ne/
to talk nonsense, rave
“Il t'est permis de te taire, Axel, quand tu voudras déraisonner de la sorte.” — You shall have my leave to hold your tongue, Axel, but not to talk in that irrational way.
From déraison + -er. Cf. also Old French deraisnier.