noun
The chemical element arsenic, atomic number 33. Often discussed in contexts of toxicity, poisoning, or semiconductor use.
ヒ素は猛毒として知られている。
Arsenic is known as a deadly poison.
この井戸水から微量のヒ素が検出された。
Trace amounts of arsenic were detected in this well water.
The kanji 素 means 'element', and ヒ is a phonetic ateji for 'arsenic'. The reading ひそ is derived from the Dutch 'arseen' or possibly German 'Arsen'.