adjective lu·cid \ ˈlü-səd \
Updated on: 14 Mar 2018

Definition of lucid

1 a : suffused with light : luminous
b : translucent
  • snorkeling in the lucid sea
2 : having full use of one's faculties : sane
3 : clear to the understanding : intelligible





lucid was our Word of the Day on 06/05/2016. Hear the podcast!

Examples of lucid in a Sentence

  1. The stroke also set off a major crisis of presidential succession, as the debilitated and not entirely lucid president continued to cling to office and plan feebly for re-election. —Beverly GageNew York Times Book Review13 Dec 2009
  2. His lucid history of this grim subject is scrupulously accurate, so far as I am able to judge … —Richard A. PosnerNew Republic8 Apr 2002
  3. "You would like me to read to you?" "You would oblige me greatly by doing so, Dorothea," said Mr. Casaubon, with a shade more meekness than usual in his polite manner. "I am wakeful: my mind is remarkably lucid." —George EliotMiddlemarch1872
  4. The atmosphere, seen through a short space of half or three-quarters of a mile, was perfectly lucid, but at a greater distance all colours were blended into a most beautiful haze … —Charles DarwinThe Voyage of the Beagle1839
  5. He is able to recognize his wife in his lucid moments.

  6. those lucid bands that spread across the arctic sky and are known as the northern lights

Recent Examples of lucid from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lucid.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Shine a Light on the Origin of lucid

It's easy enough to shed some light on the origins of lucid: it derives—via the Latin adjective lucidus, meaning "shining"—from the Latin verb lucēre, meaning "to shine." Lucid has been used by English speakers since at least the late 16th century. Originally, it meant merely "filled with light" or "shining," but it has since developed extended senses describing someone whose mind is clear or something with a clear meaning. Other shining examples of lucēre descendants include translucent, lucent ("glowing"), and the somewhat rarer relucent ("reflecting light" or "shining"). Even the word light itself derives from the same ancient word that led to lucēre.

Origin and Etymology of lucid

Latin lucidus, from lucēre — see lucent

Synonym Discussion of lucid

clear, perspicuous, lucid mean quickly and easily understood. clear implies freedom from obscurity, ambiguity, or undue complexity.
    • clear instructions
perspicuous applies to a style that is simple and elegant as well as clear.
    • a perspicuous style
lucid suggests a clear logical coherence and evident order of arrangement.
    • a lucid explanation

LUCID Defined for English Language Learners


Definition of lucid for English Language Learners

  • : very clear and easy to understand

  • : able to think clearly

LUCID Defined for Kids


adjective lu·cid \ ˈlü-səd \

Definition of lucid for Students

1 : having or showing the ability to think clearly
  • lucid behavior
2 : easily understood
  • lucid writing


  • The problem was lucidly explained.

Medical Dictionary


adjective lu·cid \ ˈlü-səd \

medical Definition of lucid

: having, showing, or characterized by an ability to think clearly and rationally


noun, plural -ties

Seen and Heard

What made you want to look up lucid? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!


a central unit of trained personnel

Get Word of the Day daily email!

Test Your Vocabulary

Confusing Words—A Quiz

  • alice-with-tweedle-dee-and-tweedle-dum
  • I invented a brand new toaster robot and ______ it "Sir Toasts-a-Lot."
True or False

Test your knowledge - and maybe learn something along the way.


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!