(1):
(n.) Bright with the radiance of intellect; not darkened or confused by delirium or madness; marked by the regular operations of reason; as, a lucid interval.
(2):
(n.) Presenting a clear view; easily understood; clear.
(3):
(n.) Clear; transparent.
(4):
(n.) Shining; bright; resplendent; as, the lucid orbs of heaven.