
1) Act conspicuously 2) Behave ostentatiously 3) Boat type 4) Broadway musical of 1927 5) Drag racing car 6) Exhibitionist to launch ship 7) Hot dog 8) Hot-dog 9) Ostentatious performer 10) River boat 11) Steamboat
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https://www.crosswordclues.com/clue/showboat

1) Hotdog
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https://www.crosswordclues.com/clue/showboat

A showboat, or show boat, was a form of theater that traveled along the waterways of the United States, especially along the Mississippi and Ohio rivers. A showboat was basically a barge that resembled a long, flat-roofed house, and in order to move down the river, it was pushed by a small tugboat (misleadingly labeled a towboat) which was attache...
Found on
http://en.wikipedia.org/wiki/Showboat
[dragster] Showboat is a four-engined four-wheel-drive exhibition slingshot dragster, built by `TV Tommy` Ivo in the 1960s. Showboat featured four Buick nailhead V8s, linked together; two drove the rear wheels, two the front. While Ivo never liked the name, Showboat proved one of the most popular models of his cars. Showboat was Hot Rod{`}s...
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http://en.wikipedia.org/wiki/Showboat_(dragster)

floating theatre that tied up at towns along the waterways of the southern and midwestern United States, especially along the Mississippi and Ohio ... [1 related articles]
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http://www.britannica.com/eb/a-z/s/87

Showboat is British slang for to be ostentatious.
Found on
http://www.probertencyclopaedia.com/browse/ZSA.HTM

[
n] - a river steamboat on which theatrical performances could be given (especially on the Mississippi River)
Found on
http://www.webdictionary.co.uk/definition.php?query=showboat
noun a river steamboat on which theatrical performances could be given (especially on the Mississippi River)
Found on
https://www.encyclo.co.uk/local/20974
No exact match found.