Effective a. : Having the power to produce an effect or effects; producing a decided or decisive effect; efficient; serviceable; operative; as, an effective force, remedy, speech; the effective men in a regiment.

Effective n. : That which produces a given effect; a cause.

Effective n. : One who is capable of active service.

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

Example:
How Effective does animal testing alternatives work such as computer modelling and human tissue cultures?

Taxonomy
Merriam-Webster Online Dictionary, Dictionary, fec, webster, Word Games, fek, tiv, rate of interest, Webster Online Dictionary with audio pronunciations, adjective, ef, thesaurus, effectual, efficacious, glossary, english, language, ESL.

Defination from the web:
effective from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... synonyms effective, effectual, efficient, efficacious mean producing or capable of producing a result. ...