Definition of "efficacy" []

• Power or capacity to produce a desired effect; effectiveness. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "It has been shown to have long-term efficacy, meaning it could be administered in small doses, potentially reducing severity of side effects."
• "The rise in efficacy of “Terrorism” is largely from the increased availability in inexpensive but highly effective weapons and equipment."
• "More information on the homeopathic treatment of mental illness and more scientific evidence verifying its efficacy is contained in a newly published textbook on the subject, Homeopathy and Mental Health Care: Integrative Practice, Principles, and Research."