A thumb thats exceedingly wide and short. Like a chode but its a thumb, hence chumb. See Megan Fox's thumbs for an example!!
A: OMG look at her thumb its so wide and short!! Who has thumbs like that??
B: Oh yeah she's got a chumb!!
B: Oh yeah she's got a chumb!!
by Sickskier1 February 20, 2011
chumbs up!
by Jon Queerbeck January 27, 2012
by Kaila Mayo January 25, 2008
by Pineapplesjee April 05, 2019