Why did you quit your job? Why are you laughing? [=what are you laughing about?] Why is the sky blue? Define why. why synonyms, why pronunciation, why translation, English dictionary definition of why. adv. For what purpose, reason, or cause; with what intention, justification, or motive: Why is the door shut? Why do birds sing? conj. 1. The reason, cause. Synonyms for WHY: oh, no, what, hey, well, gee, indeed, ha, hello, ah the cause or intention underlying an action or situation, especially in the phrase `the whys and wherefores' The meaning of WHY is for what cause, reason, or purpose. How to use why in a sentence. Why most often refers to: Causality, a consequential relationship between two or more events Reason (argument), a premise in support of an argument, for what reason or purpose Grounding (metaphysics), a topic in metaphysics regarding how things exist in virtue of more fundamental things Why?, one of the Five Ws used in journalism Why may also. 4 meanings: 1. a. for what reason, purpose, or cause? b. (used in indirect questions) 2. for or because of which 3. the reason. Click for more definitions. WHY meaning: 1. for what reason: 2. used to express surprise or anger: 3. the reasons for something. Learn more. WHY definition: 1. for what reason: 2. used to express surprise or anger: 3. the reasons for something. Learn more. Why? A question as old as humanity, and as relevant today as ever. Explore the history, meaning, and necessity of the question that drives discovery from toddlers to theoretical physicists.