It's possible you might be referring to one of these concepts:
* Body Paragraphs: In an essay or other longer piece of writing, the body paragraphs make up the main part of the text. They develop the main points and arguments presented in the introduction and provide evidence, examples, and analysis to support the thesis statement.
* Body of Work: This refers to the entire collection of written works by a particular author or artist. It could include books, poems, essays, articles, plays, or any other written form.
* Body of Evidence: This is a term used in legal and academic contexts to describe the collection of facts, information, and materials that support a claim or argument.
If you can provide more context about where you encountered the term "body of composition," I might be able to give you a more specific answer.