must

1. Origins, structure, and basic meaning

• Structure: The on reading is す, and no kun reading is listed. It has 12 strokes. It appears in words for mandatory requirements and teapots.
• Basic usage: 必須 is read ひっす and 急須 is read きゅうす.

2. Common pitfalls and similar expressions

• 必須 / 急須
  • 必須 means required or mandatory and is read ひっす. It describes a mandatory requirement such as showing identification or submitting a report.
  • 受付では身分証明書の提示が必須です。 means “Identification is required at check-in.”
  • 急須 means teapot and is read きゅうす. It refers to a teapot used to steep tea leaves in water.
  • 急須に茶葉を入れ、少し冷ました湯を注いだ。 means “I put tea leaves in the teapot and poured in water that had cooled slightly.”