隠いん顕けんインク

noun

invisible ink

Ink that is invisible under normal light but can be made visible by heat, chemical reaction, or UV light. Often used in security printing or novelty items.

• この手て紙がみは隠いん顕けんインクで書かかれている。

  This letter is written in invisible ink.

• 隠いん顕けんインクは紫し外がい線せんを当あてると浮うかび上あがる。

  Invisible ink becomes visible when exposed to ultraviolet light.