The Collaborative International Dictionary of English v.0.48:

jitters \jitters\ n.
   an uneasy state; nervousness; as, the prospect of being
   drafted gave him a bad case of the jitters.

   Syn: nervousness, nerves, screaming meemies.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

jitters
    n 1: extreme nervousness [syn: jitters, heebie-jeebies,
         screaming meemies]

Moby Thesaurus II by Grady Ward, 1.0:

81 Moby Thesaurus words for "jitters":
   agitation, all-overs, apprehension, apprehensiveness, bluster,
   bobbery, boil, boiling, brouhaha, bustle, churn, cold shivers,
   cold sweat, commotion, conturbation, discomposure, disorder,
   disquiet, disquietude, disturbance, dither, dithers, ebullition,
   embroilment, excitement, ferment, fermentation, fever,
   feverishness, fidgets, flap, flurry, fluster, flutteration, foment,
   fume, fuss, heebie-jeebies, hubbub, hurly-burly, inquietude,
   jimjams, jumpiness, jumps, maelstrom, malaise, moil, nerves,
   nerviness, nervosity, nervousness, perturbation, queasiness,
   quivers, restlessness, roil, rout, row, seethe, seething, shakes,
   shivers, skittishness, stir, sweat, swirl, to-do, trembles,
   trepidation, trepidity, tumult, tumultuation, turbidity,
   turbulence, turmoil, twitter, unease, uneasiness, unrest, upset,
   willies