Effectual means producing the result you wanted or intended. When a remedy is effectual, it actually works to solve the problem. When a leader takes effectual action, things genuinely change for the better.

The word emphasizes real results and the complete achievement of a purpose. A student might try several study methods before finding one that's truly effectual for memorizing vocabulary. A doctor prescribes medicine that proves effectual in treating an illness, meaning the patient actually gets better.

Effectual is closely related to effective, and the two words are often interchangeable. However, effectual tends to emphasize the complete achievement of a purpose, while effective can also describe something that simply works well. If you're unsure which to use, effective is the more common choice in everyday speech.

The opposite is ineffectual, describing actions or efforts that fail to produce the desired result. An ineffectual attempt to stop a playground argument might leave everyone still angry, while an effectual intervention would actually resolve the conflict and restore calm.