アヘン

• アヘンUsage61%
  kana-only spelling

  Usually written in katakana; usually written in kana.

• 阿あ片へんUsage25%

  Kanji form; rarely used in modern Japanese.

• あへんUsage13%

  Hiragana spelling, also common.

• 鴉あ片へんUsage<1%
  rarely-used kanji form

  Rarely used kanji form.

From English 'opium', via Dutch or Portuguese. The kanji forms are ateji.