| Word | Definitions | Synonyms |
|---|---|---|
| efficacious | (adjective) marked by qualities giving the power to produce an intended effect | - |
| (adjective) producing or capable of producing an intended result or having a striking effect | Synonyms: effective, effectual | |
| efficient | (adjective) being effective without wasting time or effort or expense | - |
| (adjective) able to accomplish a purpose; functioning effectively | Synonyms: effective |