—v.i. 1. to make an impression; have an effect or impact (usually fol. by on or upon): to impinge upon the imagination; social pressures that impinge upon one's daily life. 2. to encroach; infringe (usually fol. by on or upon): to impinge on another's rights. 3. to strike; dash; collide (usually fol. by on, upon, or against): rays of light impinging on the eye.