adjectives - What is the difference between 美しき and 麗しき？

What is the difference between 美しき and 麗しき and what is the difference between 美しい and 美しき?

I know that both 美しい女性 and 美しき女性 are correct. But what is the difference between these two?

Answer

Adjective Endings い and き

All the modern い adjectives used to have the following endings (more at the JA Wikipedia article, for those who can read Japanese):

• 未然形{みぜんけい} (imperfective): く



• 連用形{れんようけい} (adverbial): く


• 終止形{しゅうしけい} (terminal): し


• 連体形{れんようけい} (adnominal): き


• 已然形{いぜんけい} (perfective): けれ


• 命令形{めいれいけい} (imperative): -

The 未然形 and 連用形 are the same in modern Japanese, still ending in く. The 連体形 ending in classical Japanese was き instead of い, and folks still use that to sound old-fashioned and/or literary. So too for the 終止形 ending of し, still seen in literary use or in set phrases like よし (classical terminal form of modern 良{よ}い).

As for where the き > い shift came from, there was a time around the Muromachi period when the interstitial -k- fell out entirely for some speakers, producing forms like はやい for the 連体形 and はやう for the 連用形. This う adverbial form produced modern terms like おはよう (from 早{はや}い: はやく > はやう > はよう) or おめでとう (from 愛{め}でる: めでたく > めでたう > めでとう).

For reasons left unclear, the general population ultimately accepted the き > い shift for the 連体形, but rejected the く > う shift for the 連用形. The 連体形 and the 終止形 then merged, much as they did for verbs, leading to the disappearance of the し ending.

TL;DR: き is old-fashioned and fancified.