Addition and Subtraction poetry
Addition Poetry is a procedure in which the poet inserts characters into an existing text to make it longer, generally adding more each line. This has also been called "Larding" by Tom LaFarge. Subtraction Poetry, also known as "Erasures", removes letters from an existing text, generally removing more each line. Snowballs and Melting Snowballs (see Number Poetry) are similar but these forms are concerned only with the length of lines, not their content.
We are also including here operations done with Embedded Words: w(or)ds buried ins(id)e longer words. Art is the middle word in Earth, for example.
We also include here operations done using Implied Words: words formed from the end of o(ne w)ord and the beginnin(g o)f the next word.
Source
Dominique Fitzpatrick-O'Dinn, Writhing Society, Traditional
Examples
Johnson, Ronald: Radi Os. Phillips, Tom: A Humament. Kelon, Austin: Newspaper Blackouts.