Method and apparatus for programmatically substituting synonyms into distributed text content. A synonym substitution mechanism may programmatically replace selected words in textual data with synonyms for the selected words. The modification to an excerpt performed by the synonym substitution mechanism may not significantly alter the meaning of the excerpt to a human reader. By replacing one or more selected words in an excerpt with synonyms for the words, illicit copies of the excerpt may be recognized by comparing a copy of the excerpt to the original. Particular permutations of synonym substitutions may be provided in excerpts to particular requestors. The particular permutations may be recorded and used to determine a requestor as the source of a copy of the excerpt. Synonym substitution may make programmatic excerpt chaining difficult by substituting different synonyms for the same word(s) in an overlapping portion of two adjacent excerpts.