Not producing an intended effect:
— An ineffective teacher.
— Ineffective legislation.

synonyms: ineffectual, uneffective.

Roget 175a: uninfluential^†, ineffective; inconsequential, nugatory; unconducing, unconducive, unconducting to^†; powerless etc. 158; irrelevant etc. 10.   

Roget 732: unsuccessful, successless^†; failing, tripping etc. v.; at fault; unfortunate etc. 735.    abortive, addle, stillborn; fruitless, bootless; ineffectual, ineffective, inconsequential, trifling, nugatory; inefficient etc. (impotent) 158; insufficient etc. 640; unavailing etc. (useless) 645; of no effect.    aground, grounded, swamped, stranded, cast away, wrecked, foundered, capsized, shipwrecked, nonsuited^†; foiled; defeated etc. 731; struck down, borne down, broken down; downtrodden; overborne, overwhelmed; all up with; ploughed, plowed, plucked.    lost, undone, ruined, broken; bankrupt etc. (not paying) 808; played out; done up, done for; dead beat, ruined root and branch, flambe^†, knocked on the head; destroyed etc. 162.    frustrated, crossed, unhinged, disconcerted dashed; thrown off one's balance, thrown on one's back, thrown on one's beam ends^†; unhorsed, in a sorry plight; hard hit.    stultified, befooled^†, dished, hoist on one's own petard; victimized, sacrificed.    wide of the mark etc. (error) 495; out of one's reckoning etc. (inexpectation) 508^†; left in the lurch; thrown away etc. (wasted) 638; unattained; uncompleted etc. 730.    ... show more

Polish: bezskuteczny, bezowocny, nieskuteczny

Lacking in power or forcefulness.

synonyms: ineffectual, unable.

Roget 158: powerless, impotent, unable, incapable, incompetent; inefficient, ineffective; inept; unfit, unfitted; unqualified, disqualified; unendowed; inapt, unapt; crippled, disabled etc. v.; armless^†.    harmless, unarmed, weaponless, defenseless, sine ictu [Lat.], unfortified, indefensible, vincible, pregnable, untenable.    paralytic, paralyzed; palsied, imbecile; nerveless, sinewless^†, marrowless^†, pithless^†, lustless^†; emasculate, disjointed; out of joint, out of gear; unnerved, unhinged; water-logged, on one's beam ends, rudderless; laid on one's back; done up, dead beat, exhausted, shattered, demoralized; graveled etc. (in difficulty) 704; helpless, unfriended^†, fatherless; without a leg to stand on, hors de combat [Fr.], laid on the shelf.    null and void, nugatory, inoperative, good for nothing; ineffectual etc. (failing) 732; inadequate etc. 640; inefficacious etc. (useless) 645.    ... show more

Lacking the ability or skill to perform effectively; inadequate:
— An ineffective administration.

synonym: inefficient.

Polish: nieudaczny, nieudolny