/ Dictionary / Index A achalasia: Meaning and Definition of Find definitions for: ach•a•la•sia Pronunciation: (ak"u-lā'zhu, -zhē-u, -zē-u), [key] — n. Med. inability of a circular muscle, esp. of the esophagus or rectum, to relax, resulting in widening of the structure above the muscular constriction. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Achaemenid Achan Related Content Daily Word Quiz: simian Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language