1) Clearness 2) Clearness of thought 3) Limpidness 
• (n.) The quality of being lucent.
Lu'cen·cy noun The quality of being lucent. 
Type: Term Pronunciation: lū′sent-sē Definitions: 1. In radiology, a region in an image caused by an absorber of lower x-ray attenuation than its surrounding tissues; in general, the opposite of opacity.