This occurs when the belief exists that saying a certain word is unacceptable, either 1) because it might evoke that thing, 2) it might be considered too sacred, or 3) perhaps it is too profane. A euphemism develops so that the thing can be talked about without actually saying it. e.g., 1) Eng. bear <'the brown one' replacing the original, now lost, word probably a cognate of Grk. arktos; 2) Hebr. adonai; 3) gosh, heck or darn for certain well-known profane words.