Irrational

9 clues
Absurd
Like pi
Illogical
Incoherent
Not reasonable
Like some fears
Utterly illogical
Non compos mentis
Lacking mental clarity
Similar answers:
Additional
Additionalfood
Additionalmoney
Additionaltaxes
Adhesional
Antinationalist
Augustanational
Cirrate
Clothesoptional
Conational
Confessionalcourtesy
Congressionalidea
Congressionalpork
Constitutional
Constitutionals
Devotional
Dimensional
Educational
Educationalfilm
Educationaltoy