n.1 a poem or other composition in which certain letters in each line form a word or words.
2 a word-puzzle constructed in this way.
Phrases and idioms:
double acrostic one using the first and last letters of each line. single acrostic one using the first letter only. triple acrostic one using the first, middle, and last letters.
Etymology: F acrostiche or Gk akrostikhis f. akron end + stikhos row, line of verse, assim. to -IC