Idi*o*mat"ic*al*ly

from The Collaborative International Dictionary of English v.0.48

Idiomatic \Id`i*o*mat"ic\, Idiomatical \Id`i*o*mat"ic*al\, a.
   [Gr. 'idiwmatiko`s.]
   1. Of or pertaining to, or conforming to, the mode of
      expression peculiar to a language; as, an idiomatic
      meaning; an idiomatic phrase. -- {Id`i*o*mat"ic*al*ly},
      adv.
      [1913 Webster]

   2. Of or pertaining to, or of the nature of an {idiom}[3];
      having a meaning that is peculiar to itself and not
      predictable from general rules.
      [PJC]