Occasionally
Once In A While
adverb
Something you do accidentally is hopefully something you do occasionally or once in a while.
Also note that this word is usually written in hiragana. You'll only occasionally see it in kanji.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You haven't learned this reading yet, so here's a mnemonic to help you:
Occasionally Tamara (たま), the local ball girl, will take a break from her duties. But it's really only once in a while, because Tamara is such a hard worker.
偶にぎっくり腰になるんですよね。
I strain my back every once in a while.