bass drum

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

• noun A large drum having a cylindrical body and two heads and producing a low, resonant sound.

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

• (Mus.) The largest of the different kinds of drums, having two heads, and emitting a deep, grave sound. See bass, a.

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

• noun a large drum with a low pitch

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

• noun a large drum with two heads; makes a sound of indefinite but very low pitch