〜っこない

A casual, emphatic way of saying something is absolutely impossible; it is the colloquial equivalent of 〜わけがない or 〜はずがない. It attaches to the ます-stem of a verb and is used almost only in spoken, friendly conversation — avoid it in formal writing or with superiors. It expresses the speaker's strong conviction, not an objective fact, so it often carries a tone of giving up or dismissing an idea.

• そんな話、信じっこないよ。

  そんなはなし、しんじっこないよ。

  There's no way I'd believe a story like that.

• 一日で覚えられっこないから、少しずつ勉強しよう。

  いちにちでおぼえられっこないから、すこしずつべんきょうしよう。

  There's no way to memorize it in one day, so let's study bit by bit.

• あんな高いマンション、私の給料じゃ買えっこない。

  あんなたかいマンション、わたしのきゅうりょうじゃかえっこない。

  With my salary, I could never buy an expensive apartment like that.