/waɪ/ IPA guide Other forms: whys Definitions of why noun the cause or intention underlying an action or situation, especially in the phrase `the whys and wherefores' synonyms: wherefore Why is the US attacking Iran? The United States and Israel began strikes on Iran early on Feb. 28, in a campaign that killed the nation's supreme leader, Ayatollah Ali Khamenei, and dozens of. When we ask for reasons in speaking, we can use the phrase why is that? In informal conversations we often say why’s that?: … Drax is asking the real questions. Five key greenhouse gases are carbon dioxide, nitrous oxide, methane, chlorofluorocarbons, and water vapor. A simplified animation of the greenhouse effect. Credit: NASA/JPL-Caltech. The meaning of WHY is for what cause, reason, or purpose. How to use why in a sentence. From AI to cloud computing, data centers power today's digital world. Learn about their function and why companies are racing to build more of them. Some philosophers conclude 'Why is there something rather than nothing?' is unanswerable. They think the question stumps us by imposing an impossible explanatory demand, namely, 'Deduce the existence of something without using any existential premises'. a. for what reason, purpose, or cause?: why are you here?. b. (used in indirect questions): tell me why you're here. When we ask for reasons in speaking, we can use the phrase why is that? In informal conversations we often say why’s that?: Look, the moth is attracted to the light. Why is that? I’m not sure. She’s not going to college this year. Why’s that? She says she wants to travel for a while.