effectual

adj

1. Producing the intended result; entirely adequate.

   “Redoubling, then, the active energy of his thrusts, favoured by the fervid appetite of my motions, the soft oiled wards can no longer stand so effectual a picklock, but yield, and open him an entrance.”

   “In the living state, the body is observed to […] adopt most effectual measures for the permanent continuance of its species.”