形容詞 that end in ～しい but were not シク活用 in 古文

Question

I know that in general, if a 形容詞 in modern Japanese ends in ～しい, then it was originally a シク活用形容詞, with 終止形 ～し and 連體形 ～しき. I also know that in the Late Middle Japanese period, シク adjectives developed a 終止形 of ～しし, which then merged with ～しき and evolved into modern ～しい. But I'm wondering whether there were any ク活用形容詞 that currently end in ～しい; i.e., with classical 終止形 ～し (preceded directly by another し in the adjective root) and 連體形 ～き (but again preceded directly by し in the adjective root). It seems that just by random chance some of these could have occurred.

Again, I am not referring to the ～しし 終止形 that developed for シク adjectives in the Late Middle Japanese Period.

Thank you very much.

Answer 1

That's an interesting idea, but it actually couldn't have occurred by random chance, because it was impossible for an Old Japanese /ku/ adjective to have a stem ending in /-i/ (or, at least, no such words are attested).

A mild caveat to this: I once read (I forget where, sorry) that for many of the adjectives that came down to us in the /siku/ group, we do not have phonographic attestation in Old Japanese to prove that they were in fact /siku/ adjectives at that stage. We just assume that they were because that's how they appear in Heian-period documents. So it's technically possible that among the /siku/ adjectives there are a few that, in Old Japanese, were just /ku/ adjectives with a stem ending in /-si/, and were reanalyzed in Middle Japanese as /siku/ adjectives (roughly as you suggest could have happened).

However, given the apparent restriction on any stems ending in /-i/, and circumstantial evidence like the fact that /siku/ adjectives tend to be semantically distinctive, describing subjective or psychological states, this doesn't seem especially likely.