Merriam-Webster Collegiate Dictionary - fail

 I. verb  Etymology: Middle English ~en, from Anglo-French ~lir, from Vulgar Latin *fallire, alteration of Latin fallere to deceive, disappoint  Date: 13th century  intransitive verb  1.  a. to lose strength ; weaken her health was ~ing  b. to fade or die away until our family line ~s  c. to stop functioning normally the patient's heart ~ed  2.  a. to fall short ~ed in his duty  b. to be or become absent or inadequate the water supply ~ed  c. to be unsuccessful the marriage ~ed; specifically to be unsuccessful in achieving a passing grade took the exam and ~ed  d. to become bankrupt or insolvent  transitive verb  1.  a. to disappoint the expectations or trust of her friends ~ed her  b. to miss performing an expected service or function for his wit ~ed him  2. to be deficient in ; lack never ~ed an invincible courage — Douglas MacArthur  3. to leave undone ; neglect ~ to lock the door  4.  a. to be unsuccessful in passing ~ed chemistry  b. to grade (as a student) as not passing  • ~ingly adverb  II. noun  Date: 13th century  1. ~ure — usually used in the phrase without ~  2. a ~ure (as by a security dealer) to deliver or receive securities within a prescribed period after purchase or sale