〜極きわまる／〜極きわまりない

Meaning

Indicates that a degree is extreme beyond compare. Mostly used to strongly condemn an undesirable state, attaching to the stem of na-adjectives, as in 「失礼極まる」 (extremely rude) or 「危険極まりない」 (utterly dangerous).

Examples

連絡もなく約束を破るとは、失礼極まる態度だ。 Breaking a promise without any notice is an extremely rude attitude.
手すりもない高所での作業は、危険極まりない。 Working at heights without a railing is extremely dangerous.
彼の発言は無責任極まりないものだった。 His remarks were utterly irresponsible.