Full Definition of TUNNEL VISION. 1. : constriction of the visual field resulting in loss of peripheral vision. 2. : extreme narrowness of viewpoint: narrow-mindedness; also: single-minded concentration on one objective.— tun·nel–vi·sioned \-ˈvi-zhənd\ adjective.ull Definition of TUNNEL VISION. 1. : constriction of the visual field resulting in loss of peripheral vision. 2. : extreme narrowness of viewpoint: narrow-mindedness; also: single-minded concentration on one objective.