Mesostic

A mesostic is a poem or other text arranged so that a vertical phrase intersects lines of horizontal text. It is similar to an acrostic, but with the vertical phrase intersecting somewhere in the midst of the line, as opposed to the beginning of each line.

The practice of using index words to select pieces from a preexisting text was developed by Jackson Mac Low as "diastics". It was used extensively by the experimental composer John Cage (Walsh 2001).