acrosticism
/æk.rəˈstɪz.ɪz.əm/Definitions
1. noun
The practice of writing a message or word horizontally across a page, where each letter of the message corresponds to a letter in a word or phrase, often vertically aligned.
“The artist used acrosticism to create a hidden message in her poem, reading ‘LOVE’ vertically.”
2. noun
A poem or other work of literature that uses acrosticism.
“The professor assigned the class to read and analyze the acrostic poem in the textbook.”