effectual (adj.) Look up effectual at Dictionary.com
"producing an effect; having power to produce an effect," late 14c., Old French effectuel, from Late Latin effectualis, from Latin effectus "accomplishment, performance" (see effect (n.)). Used properly of actions (not agents) and with a sense "having the effect aimed at" (effective is used of the thing done or the agent and means "having great effect"). Related: Effectually; effectualness.