Acrostic

(Greek, ‘at the tip of the verse’)

A word, phrase, or passage spelled out vertically by the first letters of a group of lines in sequence. Sir John Davies' Hymnes of Astraea dedicates 26 acrostic poems to Elizabeth I. Edgar Allan Poe's "Enigma" provides another example. Samuel Johnson's great dictionary (1755) quotes John Dryden:

Leave writing plays, and choose for thy command
Some peaceful province in acrostick land:
There thou may'st wings display, and altars raise,
And torture one poor word ten thousand ways.