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general::
A group that makes up a majority of voters but does not widely express its views through marches or demonstrations. For example, They thought they had a convincing case, but they hadn't counted on the silent majority. This idiom was first recorded in 1874 but gained currency in the 1960s, when President Richard Nixon claimed that his policies were supported by a majority of citizens who did not bother to make their views known.
American Heritage Idioms