This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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n. A steamship, especially one used on rivers and other inland waterways.

n. A boat or vessel propelled by steam power.

n. A boat or vessel propelled by steam power; -- generally used of river or coasting craft, as distinguished from ocean steamers.

n. A vessel propelled by steam-power.

n. a boat propelled by a steam engine

"He is on white man's fire-boat, what you call steamboat, only he is on boat maybe twenty times bigger than steamboat on Yukon."

boat   

showboat   

steamship    steamer   

steamship    steamer    ferry    railway    locomotive    barge    telegraph    yacht    airship    spaceship