Merriam-Webster's Collegiate® Dictionary, 11th Edition
CAROL
I. noun see: alveolus
Date: 14th century
an old round dance with singing, a song of joy or mirth , a popular song or ballad of religious joy,
II. verb (-oled or -olled; -oling or -olling)
Date: 14th century
intransitive verb to sing especially in a joyful manner, to sing carols, transitive verb to praise in or as if in song, to sing especially in a cheerful manner ; warble , caroler or caroller noun