The Collaborative International Dictionary of English v.0.48:

Arcuation \Arc`u*a"tion\, n. [L. arcuatio.]
   1. The act of bending or curving; incurvation; the state of
      being bent; crookedness. --Coxe.
      [1913 Webster]

   2. (Hort.) A mode of propagating trees by bending branches to
      the ground, and covering the small shoots with earth;
      layering. --Chambers.
      [1913 Webster]