Unreason \Un*rea"son\, n. [Pref. un- not + reason.]

Want of reason; unreasonableness; absurdity.

Abbot of Unreason. See Abbot of Misrule, under Abbot.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Unreason \Un*rea"son\, v. t. [1st pref. un- + reason.]

To undo, disprove, or refute by reasoning. [Obs.]

To unreason the equity of God's proceedings. --South.

Source: Webster's Revised Unabridged Dictionary (1913)