- easily understood; completely intelligible or comprehensible: a lucid explanation.
- characterized by clear perception or understanding; rational or sane: a lucid moment in his madness.
- shining or bright.
- clear; pellucid; transparent.
- readily understood; clear
- shining or glowing
- psychiatry of or relating to a period of normality between periods of insane or irresponsible behaviour
adj.1590s, “bright, shining,” from Latin lucidus “light, bright, clear,” figuratively “perspicuous, lucid, clear,” from lucere “to shine,” from lux (genitive lucis) “light,” from PIE root *leuk- “to shine, be bright” (see light (n.)). Sense of “easy to understand” first recorded 1786. Lucid interval “period of calm or temporary sanity” (1580s) is from Medieval Latin lucida intervalla (plural), which was common in medieval English legal documents (cf. non est compos mentis, sed gaudet lucidis intervallis). Related: Lucidly; lucidness (1640s).