A quite common idiomatic expression in contemporary American speech is “the 600-/800-/900-/1,000-pound gorilla in the room,” which is used to mean “a very large issue that everyone is acutely aware of, but nobody wants to talk about. Perhaps a sore spot, perhaps politically incorrect, or perhaps a political hot potato, it’s something that no one wants to touch with a ten foot pole” (as defined by the Urban Dictionary). Interestingly enough, the expression started life with the word elephant instead of gorilla , i. e. “(pink) elephant in the room.” Because of its gigantism an elephant’s weight is much harder to specify than that of a gorilla, so the change of animal can be explained by the desire of the speaker to indicate just how large the undiscussed but relevant issue actually is in context.
Speaking of weight, although the variability of the beast’s poundage in the contemporary version may have something to do with the figurative force the user wishes to impart to the hidden but significant considerations at stake in discourse, this consideration is less likely than that of the sheer bulk of the animal. Ultimately, a gorilla in the public imagination looms large––especially in a room!––regardless of avoirdupois, hence the instability of its linguistic designation.