I. “+ noun
Etymology: Middle English unresoun, from un- (I) + resoun reason
1. : an act devoid of rational excuse or justification : conduct based on unconsidered impulse rather than on prudence, calculation, or morality
sought to moderate the new church; to prevent the monstrous riot and unreason which followed — A.D.White
2.
a. : the absence of reason or sanity : disorder of mind : want of rational faculty or competence : irrationality , madness
her thoughts went quickly down this ladder of unreason — Jean Stafford
this hysterical state of unreason — Dorothy C. Fisher
b. : lack of systematic or intelligible order : absence of arrangement, control, or guidance according to reasoned plan : chaos , confusion
waste, unreason , moral conflict everywhere abound — J.A.Hobson
II. transitive verb
Etymology: un- (II) + reason, n.
1. : to unhinge the reason or sanity of
2. obsolete : disprove