Source : Webster's Revised Unabridged Dictionary (1913)

Usual \U"su*al\, a. [L. usualis, from usus use: cf. F. usuel.
   See {Use}, n.]
   Such as is in common use; such as occurs in ordinary
   practice, or in the ordinary course of events; customary;
   ordinary; habitual; common.

         Consultation with oracles was a thing very usual and
         frequent in their times.                 --Hooker.

         We can make friends of these usual enemies. --Baxter.
   -- {U"su*al*ly}, adv. -- {U"su*al*ness}, n.

Source : WordNet®

usualness
     n : commonness by virtue of not being unusual [ant: {unusualness}]