The Collaborative International Dictionary of English v.0.48:

Remiss \Re*miss"\, n.
   The act of being remiss; inefficiency; failure. [Obs.]
   "Remisses of laws." --Puttenham.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Remiss \Re*miss"\ (r?-m?s"), a. [L. remissus, p. p. of remittere
   to send back, relax. See Remit.]
   Not energetic or exact in duty or business; not careful or
   prompt in fulfilling engagements; negligent; careless; tardy;
   behindhand; lagging; slack; hence, lacking earnestness or
   activity; languid; slow.
   [1913 Webster]

         Thou never wast remiss, I bear thee witness. --Milton.
   [1913 Webster]

         These nervous, bold; those languid and remiss.
                                                  --Roscommon.
   [1913 Webster]

         Its motion becomes more languid and remiss. --Woodward.
   [1913 Webster]

   Syn: Slack; dilatory; slothful; negligent; careless;
        neglectful; inattentive; heedles; thoughtless.
        [1913 Webster]

WordNet (r) 3.0 (2006):

remiss
    adj 1: failing in what duty requires; "derelict (or delinquent)
           in his duty"; "neglectful of his duties"; "remiss of you
           not to pay your bills" [syn: derelict, delinquent,
           neglectful, remiss]

Moby Thesaurus II by Grady Ward, 1.0:

87 Moby Thesaurus words for "remiss":
   Micawberish, backward, behindhand, bone-lazy, cadging, careless,
   culpably negligent, dallying, delaying, delinquent, derelict,
   dilatory, dillydallying, disregardful, do-nothing, doless, dronish,
   drony, easy, easygoing, ergophobic, faineant, foot-dragging,
   forgetful, good-for-nothing, heedless, impotent, imprecise,
   inadvertent, inattentive, indifferent, indolent, lackadaisical,
   laggard, lagging, laissez-faire, lax, lazy, lenient, lingering,
   loitering, loose, neglectful, neglecting, negligent, nonaggressive,
   noninterfering, nonrestrictive, off-guard, overindulgent,
   overly permissive, overpermissive, parasitic, permissive,
   procrastinating, procrastinative, procrastinatory, regardless,
   relaxed, scamping, scrounging, shiftless, shuffling, skimping,
   slack, slighting, slipshod, sloppy, slothful, slow, sluggish,
   slurring, soft, sponging, thoughtless, uncircumspect,
   unenterprising, unguarded, unheeding, unmindful, unrestrained,
   unrigorous, unthinking, unwary, unwatchful, weak, work-shy