What is "double acrostic"

Acrostic \A*cros"tic\, n. [Gr. ?; ? extreme + ? order, line, verse.]

1. A composition, usually in verse, in which the first or the last letters of the lines, or certain other letters, taken in order, form a name, word, phrase, or motto.

2. A Hebrew poem in which the lines or stanzas begin with the letters of the alphabet in regular order (as Psalm cxix.). See Abecedarian.

   Double acrostic, a species of enigma (crossword puzzle), in which words are to be guessed whose initial and final letters form other words.

n. A poem whose stanzas, except the first two, are clues for words. The initial letters of these words, in order, form a word clued by the first stanza; the final letters, the second stanza.