1. not producing an intended effect

- an ineffective teacher

- ineffective legislation

Similar word(s): idle, toothless, unproductive, inefficacious, inefficient, powerless, useless, ineffective, uneffective

2. producing no result or effect

- the therapy was ineffectual

Similar word(s): useless, futile, meaningless, otiose, unavailing

3. lacking in power or forcefulness

- an ineffectual ruler

Similar word(s): impotent, ineffective, unable

Sentences with ineffectual as an adjective:

- After several ineffectual and abortive leaps, we were forced to lift him over the obstacle.

- Our group leader proved highly ineffectual, caving to every whim put forth by the other members.