| Word | Definitions | Synonyms |
|---|---|---|
| efficaciousness | (noun) capacity or power to produce a desired effect | Synonyms: efficacy |
| efficacy | (noun) capacity or power to produce a desired effect | Synonyms: efficaciousness |
| efficiency | (noun) skillfulness in avoiding wasted time and effort | - |
| (noun) the ratio of the output to the input of any system | - | |
| effigy | (noun) a representation of a person (especially in the form of sculpture) | Synonyms: image, simulacrum |