third hand adjective 2noun 2forms 3 adjective2 •Having been relayed by two intermediate sources.I heard the story from someone who got it from the horse's mouth. You're getting it third hand. •Not new, having more than one previous owner. noun2 •A source two steps removed from direct communication. •A tool used to squeeze caliper brakes against the rim of a wheel, as on a bicycle, thereby allowing adjustments to the brake cable. formsthird hands · more third-hand · most third-hand