<p><strong>Verb (used without object)</strong></p><ul><li>to fall short of success or achievement in something expected, attempted, desired, or approved: The experiment failed because of poor planning.</li><li>to receive less than the passing grade or mark in an examination, class, or course of study: He failed in history.</li><li>to be or become deficient or lacking; be insufficient or absent; fall short: Our supplies failed.</li><li>to dwindle, pass, or die away: The flowers failed for lack of rain.</li><li>to lose strength or vigor; become weak: His health failed after the operation.</li><li>to become unable to meet or pay debts or business obligations; become insolvent or bankrupt.</li><li>(of a building member, structure, machine part, etc.) to break, bend, crush, or be otherwise destroyed or made useless because of an excessive load.</li><li>to stop functioning or operating: The electricity failed during the storm.</li><li>Slang: to make an embarrassing or humorous mistake, be in a humiliating situation, etc., and be subject to ridicule: Showed up late to the wedding? You fail!</li><li>to be embarrassingly incompetent, stupid, etc.: She fails at life.</li><li>to be bad or of inferior quality: The play is terrible—even the music fails.</li></ul><p><strong>Verb (used with object)</strong></p><ul><li>to be unsuccessful in the performance or completion of: He failed to do his duty.</li><li>(of some expected or usual resource) to prove of no use or help to: His friends failed him. Words failed her.</li><li>to receive less than a passing grade or mark in: He failed history.</li><li>to declare (a person) unsuccessful in a test, course of study, etc.; give less than a passing grade to: The professor failed him in history.</li></ul><p><strong>Noun (Slang)</strong></p><ul><li>an embarrassing or humorous mistake, humiliating situation, etc., that is subject to ridicule and given an exaggerated importance: Their app update is a massive fail.</li><li>the condition or quality resulting from having failed in this way: His online post is full of fail.</li><li>a person who fails in this way.</li><li>Stock Exchange: a stockbroker's inability to deliver or receive security within the required time after sale or purchase; such an undelivered security.</li><li>Obsolete: failure as to performance, occurrence, etc.</li></ul><p><strong>Interjection (Slang)</strong></p><ul><li>(used to mock an embarrassing or humorous mistake, humiliating situation, etc., giving it an exaggerated importance): A tattoo that misspells your name? Fail!</li><li>(used to indicate that something is bad or of inferior quality).</li></ul><p><strong>Adjective</strong></p><ul><li>unsuccessful; failed: a totally fail policy.</li><li>Slang: of or noting an embarrassing or humorous mistake, humiliating situation, etc.: the top 100 funniest fail photos on the internet.</li><li>embarrassingly incompetent, stupid, etc.: Why am I so fail?</li><li>very bad or of inferior quality.</li></ul>