っきり

only, just, ever since; with nothing more afterward

→ きり
preposition Rare #36,992
only, just Often attaches to a number or demonstrative; 一人っきり means “all alone.”
JA: 今日はこれっきりにしよう。
EN: Let’s call it a day here.
ever since; with nothing more afterward Often follows a past-tense verb to say there has been no further action or contact.
JA: 彼とはあの日会ったっきり、連絡がない。
EN: I haven’t been in touch with him since the day I met him.
Forms of きり
きりっきり

これっきり縁を切るわ――ジャズとお酒にそして女をだます――男たち

I’m cutting ties for good—with jazz, booze, and men who deceive women.

— シカゴ (2002)

彼は一人っきりである。

He is all alone.

早退したいってそれっきり…

I said I wanted to leave early, and that was it…

— サイコ (1960)

一人っきりより、二人の方が楽しいよ。

It's more fun with two than all by yourself.