Unconventional

a. [UN-¹ 7.] Not limited or bound down by convention; free and easy.

  Also, in recent use, unconventionally adv.

1839.  G. Darley, Beaumont & Fletcher’s Wks., I. Introd. p. xxxii. The unsettled and unconventional state of our language at that period.

1861.  [H. S. Cunningham], Wheat & Tares, 387. His views as to grammar were entirely unconventional.

1884.  E. Drew, Elocutionist, Nov., 3/1. The book … is entirely unconventional.

  Hence Unconventionalism.

1868.  Round Table, No. 202. 374. The freedom and unconventionalism in such writing.

1883.  Nonconf. & Indep., 28 Dec., 1167. The work needs freshness and unconventionalism.