Definition of "acrostick"

[L]et him that is melancholy [...] apply his minde I ſay to Heraldry, Antiquity, invent Impreſſes, Emblemes; make Epithalamiums, Epitaphs, Elegies, Epigrams, Palindrona Epigrammata, Anagrams, Chronograms, Acroſticks, upon his friends names; [...]

1638, Democritus Junior for Henry Cripps, partition 2, section 2, member 4, page 282

And afterwards gives as many reaſons for it, as there are letters in Hibernaculum Ciconiarum, and that too in the Acrostick way, each ſentence beginning with a letter of thoſe words, according to their order.

1684 August 30, “Disquisitio de Magia Divinatrice & Operatrice &c. Auctore Francisco Moncæio 4º Francofurti & Lipsiæ 1683 [book review]”, in Philosophical Transactions: Giving Some Accompt of the Present Undertakings, Studies and Labours of the Ingenious in Many Considerable Parts of the World, volume XIV, number 162, London: Printed by T. R. for John Martyn, printer to the Royal Society; […], published 1670, pages 707–708

But ſhould this Method fail, recourſe might be had to others more effectual, by Learned Men called Acroſticks and Anagrams. Firſt, might be found Men of Skill and Penetration who can diſcern that all initial Letters have political Meanings.

1726 October 28, [Jonathan Swift], “A Further Account of the Academy. […]”, in Travels into Several Remote Nations of the World. […] [Gulliver’s Travels], volume II, London: […] Benj[amin] Motte, […], part III (A Voyage to Laputa, Balnibarbi, Glubbdubdribb, Luggnagg, and Japan), page 92

The Whole [of the Book of Zephaniah] is wrote in a very lively, tender, and pathetic Stile; and all the Chapters, except the laſt, (which ſeems to have been of later Compoſition than the reſt) are in Acroſtick Verſe, i.e. every Line, or Couplet, begins, in an Alphabetical Order, with ſome Letter in the Hebrew Alphabet.

1744, Thomas Stackhouse, “From the Death of Josiah to the Babylonish Captivity”, in A New History of the Holy Bible, from the Beginning of the World, to the Establishment of Christianity. […], 2nd edition, London: Printed for Stephen Austen, […], book VI, footnote, page 950

I became a contributor to things monthly. I produced charade upon charade, rebus upon rebus, and acrostick upon acrostick, to the admiration of every body except my parents. Poor people! they were devoid of taste, and knew not the value of such a son.

1828 March 1, “Confessions over a Bottle”, in The Paisley Magazine, volume I, number 3, Paisley, Renfrewshire: David Dick, page 109