Descriptive Acrostic: This is the most accurate and specific term, as it directly describes the process of finding descriptive words for each letter of a word.
Acrostic: This is a more general term that describes any form of poetry or writing where the first letter of each line spells out a word or phrase. However, it can be used in this context as well.
Letter-by-Letter Description: This is a more straightforward way to describe the technique, but it might not be as elegant as "descriptive acrostic."
Wordplay: This is a broad term that encompasses various forms of playing with words, including acrostics, puns, and other word games.
Ultimately, the best term depends on the specific context and how you want to emphasize the technique.