Latin effectīvus practical, equivalent. to effect(us), past participle of efficere (see effect) + -īvus -ive
Middle English 1350–1400
1.See corresponding entry in Unabridged capable, competent. Effective,effectual,efficacious,efficient refer to that which is able to produce a (desired) effect. Effective is applied to that which has the power to, or which actually does, produce an effect:an effective action, remedy, speech.Effectual is used esp. of that which produces the effect desired or intended, or a decisive result:An effectual bombardment silenced the enemy.Efficacious suggests the capability of achieving a certain end:an efficacious plan, medicine.Efficient (applied also to persons) implies the skillful use of energy or industry to accomplish desired results with little waste of effort:efficient methods; an efficient manager.
2.See corresponding entry in Unabridged operative.
3.See corresponding entry in Unabridged telling.
1.See corresponding entry in Unabridged futile, useless.