厄介 [やっかい] – trouble; burden; bother

  • 厄 [ヤク] – bad luck; misfortune; disaster
  • 介 [カイ] – concern oneself with

You’ll notice by looking at the pronunciation, you’d expect this word to be pronounced やくかい.  However, allowing a く to lead right into a か isn’t considered euphonic.  To fix this, the Japanese will often omit the first syllable and replace it with a small っ, which indicates that the next consonant sound should be doubled.  Thus, やくかい is rendered thus: やっかい.  This happens in many other cases where the first syllable is く or ち:

  • 一回 one time:  いち+かい = いっかい
  • 各国 all countries:  かく+こく = かっこく