Think of an important event in history, such as the development of the United States Constitution. Narrow your term to a single definable element, such as "Equality as seen in the Constitution."
Research the different meanings and applications of your term in your school library, public library or on the Internet. Choose details and examples that apply to your term and that you want to include in your essay.
Write a thesis showing your intent to define the term and the method of definition. For example, "Equality is defined by history as the right for all people to life, liberty and the pursuit of happiness." The thesis statement will act as the backbone of your essay, and will need to be proven by historical examples illustrating your points.
Create an outline determining what you will discuss in each paragraph of your definition essay. For example, make a list of each main point of your thesis for each body paragraph in your essay, such as:
A. Equality delegated to minorities
1. African-Americans and slavery
2. Women and the right to vote
3. Gay marriage
Draft the introduction of the definition essay beginning with the "what" and "why" of the essay. For example, the "what" of a historical definition essay discussing equality could begin like this: "John Locke's theory of natural rights and equality became implemented into the Constitution of the United States by America's founding fathers." The "why" of the essay could be: "Even so, the idea of equality in the Constitution remains to this day somewhat shrouded by misinterpretations and personal agendas." The rest of the introduction should explain your intent to define the historical term and your method of doing so. This should be explained by your thesis.
Draft the body paragraphs according to your outline. Explore the main idea of your body paragraphs by introducing the definition for each main point, an example of that definition and an analysis of how the example illustrates your point.
Draft the conclusion of the essay by summarizing the main points discussed within the body. When restating the thesis, use different wording to avoid redundancy. The ideal conclusion clarifies to readers what to take away from the essay: why should they care about the term and definition? To nail this point, make use of techniques such as a call to action, a quotation linking back to the introduction, vital statistics or completion of an anecdote started in the introduction.
Proofread the essay for mistakes in grammar. Look out for overuse of passive sentences that can confuse and bore the audience, such as: "Locke's and other philosophers' ideas were then used as the basis for beginning to write the Constitution." The same sentence written actively would read: "Locke's and other philosophers' ideas became the basis for writing the Constitution."
Reference any outside material you used according to your instructor's guidelines, if any. Essays written in the humanities are usually cited according to the Modern Language Association (MLA) format.