wiper arm(n = noun.artifact) contact arm, wiper - contact consisting of a conducting arm that rotates over a series of fixed contacts and comes to rest on an outlet;
is a kind of contact, tangency
is a part of rheostat, variable resistor, selector, selector switch

arm, arm band, arm bone, arm exercise, arm guard, arm in arm, arm pad, contact arm, light arm, pickup arm, rocker arm, side arm, strong arm, tone arm, windscreen wiper, windshield wiper, wiper, wiper blade, wiper motor, writing arm