Meaning

adjective (of language) transparently clear; easily understandable; ; ; - Robert Burton

adjective having a clear mind

adjective capable of thinking and expressing yourself in a clear and consistent manner

originEtymology tree Proto-Indo-European *lewk- Proto-Indo-European *-yeti Proto-Indo-European *-éyeti Proto-Indo-European *lowkéyeti Proto-Italic *loukeō Proto-Indo-European *lewk-der. Proto-Italic *loukēō Latin lūceō Proto-Indo-European *dʰeh₁-der. Proto-Italic *-iðos Latin -idus Latin lūcidus English lucid Latin lucidus, from lūceō (“shine”) + -idus.

Etymology from Wiktionary, CC BY-SA 3.0