The area on a ship where the steering wheel is located, or someone's area of expertise and comfort.
Nautical compound: 'wheel' (ship's steering wheel) + 'house' (enclosed shelter). Used literally on ships since the 1600s, then metaphorically for 'one's specialty' by the 1900s.
The phrase 'in someone's wheelhouse' comes directly from the captain's command position—the one place where the captain had absolute control and complete confidence.
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