Webster's Revised Unabridged Dictionary · 1913

Insuetude

Insuetude , noun

[Latin insuetudo, from insuetus unaccustomed; pref. in- not + suetus, past participle of suescere to be accustomed.]

The state or quality of being unaccustomed; absence of use or habit.
Absurdities are great or small in proportion to custom or insuetude. — Landor