kingpin
noun
°(motorized vehicles) The axis around which steered wheels pivot; a bolt that holds the axis in place—a kingbolt.
°(ten pin bowling) The pin at the centre of the triangle of bowling pins (originally the tallest pin in kayles). Sometimes also the headpin at the apex.
synonyms: big cheese, big enchilada, big kahuna, bigwig more» , big wheel, grand poobah, head honcho, muckety muck, top banana, top dog, big noise