How to say "inadvertently" in Japanese

• うっかりJLPT N2approx.Common
  adverb (with と), suru verbCovers the careless-slip sense of 'inadvertently': doing something through a momentary lapse of attention or thought. Typical contexts include forgetting something or saying something you did not mean to say.
  うっかりそれを忘わすれるところだったわ。↗

  I almost forgot all about that.
• 何気なくなにげなくCommon
  expression, adverbCovers the 'without intending anything by it' sense: doing or saying something casually, offhandedly, or innocently. It suits mentioning something in passing without realizing it might matter, rather than a momentary careless slip.

Use 「うっかり」 for a momentary careless slip done through a brief lapse of attention, and 「何気なく」 for doing or saying something casually and offhandedly, without intending anything particular by it.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• うっかりcarelessly
• 何気なくなにげなくunintentionally
• 何気になにげにinadvertently
• くっとinadvertently (letting out a laugh)
• 何の気なしになんのきなしにunintentionally
• 意図せずいとせずunintentionally
• 巧まずしてたくまずしてunintentionally
• ぽろりinadvertently (coming to the surface)
• ポロっとinadvertently (coming to the surface)