In a short 1814 fable from Russian poet Ivan Krylov, the Inquisitive Man spends three hours at a natural history museum and tells his friend he "saw everything there was to see and examined it carefully" and found it "all so astonishing." The friend then asks what he thought of the elephant. The man retorted: "(D)on't tell anybody—but the fact is that I didn't notice the elephant!"
That is the origin of the phrase, "the elephant in the room." It means, as Cambridge Dictionary explains, "an obvious problem or difficult situation that people do not want to talk about." There are many reasons people ignore a 10,000-lb. creature blocking their way, but often it involves cowardice. It's too hard—or controversial—to discuss how it got there and how to get rid of it.
