1560s, perhaps via Middle French élucider (15c.) or directly from Late Latin elucidatus, past participle of elucidare “make light or clear,” from assimilated form of ex “out, away” (see ex-) + lucidus “light, bright, clear,” figuratively “perspicuous, lucid, clear,” from lucere “to shine,” from PIE root *leuk- “to shine, be bright.” Related: Elucidated; elucidates; elucidating.