The Collaborative International Dictionary of English v.0.48:

nonparallel \nonparallel\ adj.
   1. not parallel; -- of lines or linear objects. Opposite of
      parallel. [Narrower terms: bias, catacorner,
      cata-cornered, catercorner, cater-cornered, catty-corner,
      catty-cornered, diagonal, kitty-corner, kitty-cornered,
      oblique, skew, skewed, slanted ; {crossed, decussate,
      intersectant, intersecting; cross-grained ; {diagonal;
      orthogonal, orthographic, rectangular, right-angled ;
      {right, perpendicular; angled ; {convergent] Also See:
      convergent, divergent, diverging.
      [WordNet 1.5]

   2. (Computers) Not using parallel processing; -- of
      computers. [Narrower terms: serial] PJC]

WordNet (r) 3.0 (2006):

nonparallel
    adj 1: of or relating to the sequential performance of multiple
           operations; "serial processing" [syn: serial, in
           series(p), nonparallel]
    2: (of e.g. lines or paths) not parallel; converging