The Collaborative International Dictionary of English v.0.48:

Shaggy \Shag"gy\, a. [Compar. Shaggier; superl. Shaggiest.]
   [From Shag, n.]
   Rough with long hair or wool.
   [1913 Webster]

         About his shoulders hangs the shaggy skin. --Dryden.
   [1913 Webster]

   2. Rough; rugged; jaggy. --Milton.
      [1913 Webster]

            [A rill] that winds unseen beneath the shaggy fell.
                                                  --Keble.
      [1913 Webster]

WordNet (r) 3.0 (2006):

shaggy
    adj 1: used of hair; thick and poorly groomed; "bushy locks"; "a
           shaggy beard" [syn: bushy, shaggy, shaggy-haired,
           shaggy-coated]
    2: having a very rough nap or covered with hanging shags;
       "junipers with shagged trunks"; "shaggy rugs" [syn:
       shagged, shaggy]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "shaggy":
   bristly, broken, bumpy, bushy, choppy, cirrose, coarse,
   coarse-grained, corrugated, cross-grained, disheveled, fleecy,
   flocculent, furry, fuzzy, grainy, granulated, hairy, hirsute,
   hispid, homespun, horripilant, inequal, irregular, jolty, knobbed,
   lanate, linsey-woolsey, matted, messed up, mussed up, nappy,
   nubbly, nubby, pilose, pily, pimply, pitted, pocky, potholed,
   pubescent, rank, ripply, rough, rough-cast, rough-grained,
   rough-hewn, ruffled, rumpled, rutted, rutty, shagged, snaggy,
   snarled, studded, textured, tousled, tously, tumbled, uncombed,
   uncut, uneven, unkempt, unlevel, unpolished, unrefined, unshorn,
   unsmooth, untidy, ununiform, wimpled, woolly