What is the difference between [極み]{きわみ} and [極まり]{きわまり}? And how do they compare to [至り]{いたり}?
- What kind of scenarios are they each used in?
- Are they ever interchangeable?
What is the difference between [極み]{きわみ} and [極まり]{きわまり}? And how do they compare to [至り]{いたり}?
As a prerequisite, please read: Conjunctive form (e.g. 書き) vs Conj + mono (e.g. 書き物)
極み is a lexicalized noun on its own. Etymologically, it's the masu-stem of 極む, but 極む has already fallen out of use, and only 極み remains in modern Japanese. It's used in two ways:
極まり is simply the masu-stem of the common godan verb 極まる, and it does not have a special meaning as a lexicalized noun. If you know the usage of masu-stem in general, such as in "朝食を食べ出社する", there is nothing more to it.
至り is also simply the masu-stem of 至る, so it's typically used like "40歳に至り記憶力の衰えを感じます". 至り is also sometimes used as a lexicalized noun meaning "utmost", and 若気の至り and 光栄の至り are common set phrases. However, 至り is not very common outside these; 極み is generally preferred today, especially when saying something negative (痛恨の極み, 後悔の極み).