The Collaborative International Dictionary of English v.0.48:

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.
   [1913 Webster]

         Consultation with oracles was a thing very usual and
         frequent in their times.                 --Hooker.
   [1913 Webster]

         We can make friends of these usual enemies. --Baxter.
   [1913 Webster] -- U"su*al*ly, adv. -- U"su*al*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

usualness
    n 1: commonness by virtue of not being unusual [ant:
         unusualness]