(in an online context) register disapproval of or disagreement with (a post or poster) by means of a particular icon

I had to resist the urge to downvote the first serious comment

you can downvote me all you want, but the refereeing this season has been absolutely deplorable

if you want to downvote, go ahead

(in an online context) an instance of using a particular icon to register disapproval of or disagreement with a post or poster

there is absolutely nothing in his comment that deserves a downvote

I am making it my mission to counter every downvote you are given for critiquing his grammar