flattop

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An aircraft carrier.
• noun A short haircut in which the hair is brushed straight up and cropped flat across the top.
• noun An acoustic guitar having a flat piece of wood on the side where the strings are, a single sound hole in the center of the body, and a bridge attached just below the sound hole.

from The Century Dictionary.

• noun An American perennial herb, Vernonia Noveboracensis. Also called iron-weed.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Mil.) An aircraft carrier.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun US A short haircut in which the hair is brushed straight up then cut flat across the top
• noun US (informal) An aircraft carrier; origin credited since 1942 to a laconic message, “Scratch one flattop,” radioed by LCDR Robert E. Dixon to USS Lexington, whose commanding officer credited the pilot with coining the standard USN slang; see Wikipedia for Battle of Coral Sea

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a large warship that carries planes and has a long flat deck for takeoffs and landings
• noun a closely cropped haircut; usually for men