Word of the day: acrostic

In the Evening Standard on Friday 1 March, there was an article entitled: Headmaster quits over hidden insult in newsletter.
The story was about a headmaster of a London independent school who quite after a newsletter with the following line had been circulated:
"We all now know every really great teacher has to finish one day and Mr Clark will do so at the end of this term."

Seemed pretty harmless to me.

An acrostic is a poem or other form of writing in which the first letter, syllable or word of each line, paragraph or other recurring feature in the text spells out a word or a message.

I personally have considered hiding messages in this way myself. Didn't know there was a name for that! You learn something new every day!