Real Dictionary

middle-of-the-road
politically neither very left-wing nor very right-wing
adjective: If you describe someone's opinions or policies as middle-of-the-road, you mean that they are neither left-wing nor right-wing, and not at all extreme.
adjective: If you describe something or someone as middle-of-the-road, you mean that they are ordinary or unexciting.
adjective: Middle-of-the-road music is pop music which a large number of people like because it is pleasant and does not sound extreme or unusual. The abbreviation MOR is also used.

middle-of-the-road in American English
avoiding extremes, esp. of the political left and right; uncommitted to either liberalism or conservatism
adjective: favoring, following, or characterized by an intermediate position between two extremes, esp. in politics; moderate
noun: popular music having comparatively conventional, melodic qualities and hence having broad commercial appeal

middle-of-the-road in British English
adjective: not extreme, esp in political views; moderate