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

• Lexulous
• Wordscraper
• Wordosaur

n. A boat that has a single hull

"The Superocean is equipped with an ultra-readable dial, an armored glass and a monohull case watertight to a depth of 200 meters 660 ft – a remarkable feat at that time."

outrigger canoe   

multihull    twinhull    trimaran    catamaran   

monohulled