The Collaborative International Dictionary of English v.0.48:

Inoperative \In*op"er*a*tive\, a. [Pref. in- not + operative.]
   Not operative; not active; producing no effects; as, laws
   renderd inoperative by neglect; inoperative remedies or
   processes. Inopercular

WordNet (r) 3.0 (2006):

inoperative
    adj 1: not working or taking effect; "an inoperative law" [ant:
           operative]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "inoperative":
   barren, bootless, broken, counterproductive, effete, empty,
   etiolated, fatuitous, fatuous, feckless, fruitless, functionless,
   futile, haywire, in disrepair, inadequate, inane, inapplicable,
   ineffective, ineffectual, inefficacious, inoperable, invalid,
   nonfunctional, nonutilitarian, nugacious, nugatory, of no force,
   on the blink, on the fritz, otiose, out of commission,
   out of condition, out of gear, out of joint, out of kelter,
   out of kilter, out of order, out of repair, out of tune,
   out of whack, sterile, unavailing, unconducive, unemployable,
   unfit, unhelpful, unsuitable, unusable, unworkable, useless,
   vain