Someone who has down syndrome, due to them acting complete incompetent.
Ross Steineke is chinless, how the hell could he fuck that up.
by midnighte May 03, 2010
A person who has no chin, often has a larger forehead to make up for the 'lack of chin'
OH MY LOOK AT PAUL HOWKINS, HE'S SO CHINLESS
by IizKwl March 07, 2010