What does "effectual" mean?

Effectual: Producing, or having adequate power or force to produce, an intended effect; adequate; efficient; operative; decisive. Shak. Effectual steps for the suppression of the rebellion. Macaulay. Effectual calling (Theol.), a doctrine concerning the work of the Holy Spirit in producing conviction of sin and acceptance of salvation by Christ, -- one of the five points of Calvinism. See Calvinism. An efficacious remedy is had recourse to, and proves effective if it does decided good, effectual if it does all the good desired. C. J. Smith.