cel·lo (ch?l??)n. pl. cel·los A four-stringed musical instrument of the violin family, pitched lower than the viola but higher than the double bass.[Short for violoncello.]cel?list (ch?l??st) n.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.cel?list (?t??l ?st) n. a person who plays the cello. [1885?90; short for violoncellist] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.