ineffectual

Example:The new drug was highly effective in treating the disease without any side effects.

Definition:Causing a desired or intended result; producing an effect.

Example:Her new teaching methods were highly efficient and led to significant improvements in student performance.

Definition:Achieving a desired end by the least waste of time, strength, or money; productive of the greatest possible amount or effect.

Example:His potent words had a profound effect on the audience, changing their opinions and beliefs.

Definition:Randomly paired synonym for 'effective'; characterized by great power, force, or strength.