The adverbial particle きり indicates that an action was performed once, and then a resulting state continued without the expected follow-up action occurring. It is often translated as 'since', 'only', or 'just'. The particle きり originates from the verb 切(き)る, meaning 'to cut'. It typically follows the plain past form of a verb, a noun, or a counter. We will begin by examining its use with verbs.

• 弟(おとうと)は今朝(けさ)、家(いえ)を出(で)たきりまだ帰(かえ)ってこない。
  My younger brother left the house this morning and still hasn't come back.
• 彼(かれ)は五年(ごねん)前(まえ)アメリカへ行(い)ったきり、連絡(れんらく)がない。
  He went to America five years ago, and I haven't heard from him since.

When used with verbs, きり highlights that after action (A) happened, an expected development did not follow, and things have remained in that state since. This often implies a lasting or definitive outcome. Because (A) is presented as a singular, final event, きり can nearly always be understood to mean 'ever since that one time'.

When きり is attached to nouns or counters, it defines a clear boundary, meaning 'only' or 'just' that amount. It emphasizes that the specified noun or number is the absolute limit, with nothing else being involved.

• 彼女(かのじょ)は図書館(としょかん)でいつも一人(ひとり)きりだ。
  She is always by herself in the library.
• あのレストランには一回(いっかい)きりしか行(い)ったことがない。
  I've only ever been to that restaurant once.
• これは二人(ふたり)っきりの秘密(ひみつ)にしようね。
  Let's keep this a secret, just between the two of us.