secretpen
nounUK /ˈsiː.krət.pɛn/
US /ˈsiː.krət.pɛn/
A secret pen is a special pen you use to write messages that only certain people can read.
Mia used her secretpen to write a note to her best friend.
OTHER MEANINGS
2. A pen that hides what you write until you do something special to reveal it.
The secretpen showed the words only when you shined a light on the paper.
3. A pen used by spies or detectives to keep their writing private.
The detective carried a secretpen in his coat pocket.
4. A pen that writes in a code or puzzle language.
She wrote the treasure map with a secretpen so only her team could solve it.