I was searching for the meaning of "時すでに遅し。" but I couldn't find 遅し in the dictionary goo.ne.jp and weblio tells me that it's おそい with 形ク in parenthesis.
1 Answer
It stands for 形容詞-ク活用【かつよう】. ク活用 is one of the two conjugation types of classical Japanese adjectives. 遅し is the archaic "dictionary" form of modern 遅い. 時すでに遅し is a fixed set phrase that preserves the archaic grammar. It just means "It is/was too late."
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