an ingenious or novel device, scheme, or stratagem, esp. one designed to attract attention or increase appeal.

a concealed, usually devious aspect or feature of something, as a plan or deal

An offer that good must have a gimmick in it somewhere.

a hidden mechanical device by which a magician works a trick or a gambler controls a game of chance.

Electronics Informal . a capacitor formed by intertwining two insulated wires.

to equip or embellish with unnecessary features, esp. in order to increase salability, acceptance, etc. (often fol. by up )

to gimmick up a sports car with chrome and racing stripes.

to resort to gimmickry, esp. habitually.

noun

aid , apparatus , artifice , catch , concern , counterfeit , deceit , device , dodge * , fake , feint , fixture , fun , gadget , gambit , game , gizmo * , imposture , instrument , jest , maneuver , means , method , ploy , ruse , secret , shift , sport , stratagem , stunt , trick , widget * , wile , deception , dodge , jig , sleight , subterfuge , contraption , contrivance , jigger , thing , twist