Source : Webster's Revised Unabridged Dictionary (1913)

Ineffectual \In`ef*fec"tu*al\ (?; 135), a.
   Not producing the proper effect; without effect; inefficient;
   weak; useless; futile; unavailing; as, an ineffectual
   attempt; an ineffectual expedient. --Pope.

         The peony root has been much commended, . . . and yet
         has been by many found ineffectual.      --Boyle.

   Syn: Inefficient; useless; inefficacious; vain; fruitless;
        unavailing; futile. See {Useless}, {Inefficacious}.

Source : WordNet®

ineffectual
     adj 1: not sufficient to produce a desired result; "an ineffectual
            effort to block the legislation" [ant: {effectual}]
     2: not producing an intended effect; "an ineffective teacher";
        "ineffective legislation" [syn: {ineffective}, {uneffective}]
        [ant: {effective}]
     3: producing no result or effect; "a futile effort"; "the
        therapy was ineffectual"; "an otiose undertaking"; "an
        unavailing attempt" [syn: {futile}, {otiose}, {unavailing}]
     4: lacking in power or forcefulness; "an ineffectual ruler";
        "like an unable phoenix in hot ashes" [syn: {ineffective},
         {unable}]