In-effectualness means lacking the ability or power to produce a desired effect. Antonyms for in-effectualness may include effectiveness, potency, power, strength, competence, efficiency, influence, and capability. If something is effective, it is successful in producing an intended result. Potency suggests the degree of effectiveness of a particular substance or action. Power refers to the ability to control or influence others. Strength implies the capacity to withstand great force or pressure. Competence suggests having the necessary skills and abilities to perform a task effectively. Efficiency means achieving maximum productivity with minimum wasted effort. Influence implies the power to sway or affect someone's behavior or decisions. Capability means having the capacity to do something.