An adjective describing what is shrouded in darkness or shadow. Jesus uses it in parallel teachings about the eye as the lamp of the body (Matt 6:23, Luke 11:34, 36). If the eye—the source of inner illumination—is 'dark,' then the whole person dwells in darkness. The classical Greek background includes both literal darkness (night, shadowy places) and metaphorical obscurity (unclear speech, hidden motives). In Jesus' teaching, a 'dark' eye suggests spiritual blindness or moral distortion that plunges the entire person into shadow.