carol

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

• noun A song of praise or joy, especially for Christmas.
• noun An old round dance often accompanied by singing.
• intransitive verb To sing in a loud, joyous manner.
• intransitive verb To go from house to house singing Christmas songs.
• intransitive verb To celebrate in or as if in song.
• intransitive verb To sing loudly and joyously.

from The Century Dictionary.

• To sing; warble; sing in joy or festivity.
• To sing joyously.
• To praise or celebrate in song.
• noun A kind of circular dance.
• noun [It is often difficult to tell from the context whether carol is the dance or the song that seems to have been sung as an accompaniment to it; but in Chaucer it usually means simply the dance.]
• noun A song, especially one expressive of joy; often, specifically, a joyous song or ballad in celebration of Christmas.
• noun A ring of leaves or flowers; a garland; a wreath.
• noun In architecture: A small closet or inclosure in which to sit and read. A bay-window.
• noun Also written carrel, carrell, carrall.

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

• transitive verb To praise or celebrate in song.
• transitive verb To sing, especially with joyful notes.
• noun (Arch.) A small closet or inclosure built against a window on the inner side, to sit in for study. The word was used as late as the 16th century. The term carrel, of the same has largely superseded its use.
• noun obsolete A round dance.
• noun A song of joy, exultation, or mirth; a lay.
• noun A song of praise of devotion.
• noun Joyful music, as of a song.
• intransitive verb To sing; esp. to sing joyfully; to warble.

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

• noun A round dance accompanied by singing.
• noun A song of joy.
• noun A religious song or ballad of joy.
• verb intransitive To sing in a joyful manner.
• verb intransitive To sing carols, especially Christmas carols in a group.
• verb transitive To praise (someone or something) in or with a song.
• verb transitive To sing (a song) cheerfully.

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

• noun a joyful song (usually celebrating the birth of Christ)
• verb sing carols
• noun joyful religious song celebrating the birth of Christ