Efficacious

efficacious\ef-uh-KAY-shus\       adjective   : having the power to produce a desired effect         Pam knew that the most efficacious remedy for her cold would be a steaming bowl of her grandmother's famous chicken soup.   "The following plan is efficacious in ridding fields not only of crows but of smaller birds and even domestic fowl: Make an imitation hawk, using a large potato and long turkey feathers…. Suspend it from a tall, bent pole. The wind will lend it realism by agitating it." — From Jerry Mack Johnson's 2011 book Old-Time Wisdom and Country Lore: 1000s of Skills for Simple Living         "Effective," "efficient," and "effectual" are synonyms of "efficacious," but each of these words has a slightly different connotation. "Efficacious" suggests possession of a special quality or virtue that makes it possible to achieve a result ("a detergent that is efficacious in removing grease"). "Effective" stresses the power to produce or the actual production of a particular effect ("an effective rebuttal"), while "effectual" suggests the accomplishment of a desired result, especially as viewed after the fact ("measures taken to reduce underage drinking have proved effectual"). "Efficient" implies an acting or potential for acting that avoids loss or waste of energy ("an efficient small car").   Test Your Memory: What recent Word of the Day begins with "p" and means "of or relating to apples"? The answer is …