What is the origin of the word 無{な}し?


The word なし, of course, means ない, and it is defined as such in dictionaries.
But why does this word exist? Are there even any situations where you can say
なし but you _can't_ say ない? Is it a remnant of something from classical
Japanese? It seems similar enough in use and meaning to ない that it doesn't
seem that it can be dismissed as its own word entirely and etymologically
separate from ない. I checked etymology sites and dictionaries and tried
googling, but I can't find any explanation for this word.




nasi and nai are the same word. Like all adjectives, nasi is the conclusive
form (終止形), while nai is the attributive form (連体形). More specifically, the
attributive ends in naki, but the medial -k- drops out in modern Japanese
becoming nai. This is true of all adjectives: atusi -> atuki > atui, takasi ->
takaki > takai, muzukasi -> muzukasiki > muzukasii etc. You can still see this
medial -k- in the adverbial form (連用形) -ku.

Note that in modern Japanese, the original conclusive was replaced by the
attributive, so it may now act as a conclusive. This is true in verbs as well.




nasi and nai are the same word. Like all adjectives, nasi is the conclusive
form (終止形), while nai is the attributive form (連体形). More specifically, the
attributive ends in naki, but the medial -k- drops out in modern Japanese
becoming nai. This is true of all adjectives: atusi -> atuki > atui, takasi ->
takaki > takai, muzukasi -> muzukasiki > muzukasii etc. You can still see this
medial -k- in the adverbial form (連用形) -ku.

Note that in modern Japanese, the original conclusive was replaced by the
attributive, so it may now act as a conclusive. This is true in verbs as well.

