1. (a.) Having the power to produce an effect or result; fit for a purpose; as, an effective tool; producing a decided or decisive effect; efficient; serviceable; operative; as, an effective force, remedy, speech; the effective men in a regiment.

2. (n.) That which produces a given effect; a cause.

3. (n.) One who is capable of active service.

4. (n.) Specie or coin, as distinguished from paper currency; -- a term used in many parts of Europe.