a suffix extracted from marathon, occurring as the final element in compounds which have the general sense “an event, as a sale or contest, drawn out to unusual length, often until a prearranged goal, as the contribution of a certain amount of money, is reached”: walkathon; readathon.
Also -a-thon, -thon.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
suffix forming nouns
indicating a large-scale event or operation of a specified kindtelethon
Word Origin for -thon
C20: on the pattern of marathon
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Online Etymology Dictionary, © 2010 Douglas Harper