expression, noun
extreme regret; height of bitterness
A strong, often formal expression for deep regret or chagrin, typically used in serious contexts such as apologies, sports commentary, or news reports.
試合に負けて、痛恨の極みです。
Losing the match is a matter of extreme regret.
彼は痛恨の極みといった表情でミスを振り返った。
He looked back on his mistake with an expression of the deepest chagrin.
Compound of 痛恨 (deep regret) + の (possessive particle) + 極み (extreme, height). The phrase follows a classical pattern for expressing the utmost degree of a feeling.