ef·fi·ca·cious  ( ĕf ′ĭ-k āsh əs)
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adj. Producing or capable of producing a desired effect. See Synonyms at effective.
[From Latin efficāx, efficāc-, from efficere, to effect; see EFFECT.]
ef′fi·cacious·ly adv. ef′fi·cacious·ness n. |
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
Indo-European Roots
Semitic Roots
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.
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