The Collaborative International Dictionary of English v.0.48:

Choppy \Chop"py\, a. [Cf. Chappy.]
   1. Full of cracks. "Choppy finger." --Shak.
      [1913 Webster]

   2. [Cf. Chop a change.] Rough, with short, tumultuous
      waves; as, a choppy sea.
      [1913 Webster]

WordNet (r) 3.0 (2006):

choppy
    adj 1: marked by abrupt transitions; "choppy prose" [syn:
           choppy, jerky]
    2: rough with small waves; "choppy seas"

Moby Thesaurus II by Grady Ward, 1.0:

139 Moby Thesaurus words for "choppy":
   bouncy, broken, broken off, bumpy, capricious, careening, catchy,
   changeable, changing, chopped-off, coarse, coarse-grained,
   corrugated, cross-grained, decousu, desultory, deviating,
   deviative, deviatory, different, disconnected, discontinued,
   discontinuous, discrete, disjunctive, disorderly, divaricate,
   divergent, diversified, diversiform, eccentric, episodic, erose,
   erratic, fitful, flickering, fluctuating, grainy, granulated,
   guttering, halting, herky-jerky, heteroclite, homespun,
   horripilant, immethodical, impulsive, incoherent, inconsistent,
   inconstant, inequal, intermittent, intermitting, interrupted,
   irregular, jagged, jarring, jerky, jogglety, joggling, joggly,
   jolting, jolty, linsey-woolsey, lurching, mercurial, motley,
   mutable, nonconformist, noncontinuous, nonlinear, nonsequential,
   nonserial, nonstandard, nonuniform, parenthetic, patchy, pimply,
   pitted, pluralistic, pocky, potholed, ragged, rambling, rank,
   ripply, rough, rough-cast, rough-grained, rough-hewn, ruffled,
   rutted, rutty, scrappy, shagged, shaggy, snatchy, spasmatic,
   spasmic, spasmodic, spastic, sporadic, spotty, staggering,
   suspended, textured, uncertain, unconnected, unequable, unequal,
   uneven, unjoined, unkempt, unlevel, unmethodical, unmetrical,
   unorthodox, unpolished, unrefined, unregular, unrhythmical,
   unsettled, unsmooth, unstable, unsteady, unsuccessive,
   unsystematic, ununiform, variable, variegated, variform, various,
   varying, veering, wandering, wavering, wimpled, wobbling, wobbly