billy goat

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

• noun A male goat.

from The Century Dictionary.

• noun A familiar name for a he-goat, as nanny-goat is for a she-goat.

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

• colloq. A male goat.

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

• noun A male goat.

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

• noun male goat