lucid

läpikuultava, läpinäkyvä

selväpäinen, selväjärkinen

selkeä clear; easily understood
(quote-journal) (Review)|date=26 September 2014|passage=The book, constructed in short, lucid episodes, can be satisfyingly read as a sequence of provocative talks, at once well informed and vatic.
mentally rational; sane
bright, luminous, translucent or transparent
A lucid dream.
1986, Benjamin B. Wolman, Montague Ullman, Handbook of states of consciousness (page 163)

The day before nightmare-initiated lucids, subjects reported more depressed feelings(..)