a ‧ cros ‧ tic /əˈkrɒstɪk $ əˈkrɒː-/ BrE AmE noun [countable]
[ Date: 1500-1600 ; Language: French ; Origin: acrostiche , from Greek akrostichis , from akr- ( ⇨ ↑ acronym ) + stichos 'line' ]
a poem or piece of writing in which the first or last letter of each line spells a word