once

onceとは　意味・定義・例文

Adverb 副詞

1. on one occasion only

一度だけ

I only met him once, very briefly.

2. in the past

かつて, 昔, 当時

I lived there once, before I was married.

Conjunction 接続詞

1. after something happened; when or if

一旦～すると, ～するときはいつでも

Once you make a promise, you should keep it.