Explanations clarify ideas by providing information about what something is, why something is the way it is, or how something works or came to be. One of the most common types of explanation is a definition. Definitions do not have to come from the dictionary. Many times, authors will define concepts as they use them in their writing, which is a good alternative to a dictionary definition.
As you do your research, think about how much your audience likely knows about a given subject. You do not need to provide definitions when information is common knowledge. Anticipate audience confusion and define legal, medical, or other forms of jargon as well as slang and foreign words. Definitions like the following are also useful for words that we are familiar with but may not know specifics: “According to the 2011 bookProhibition: 13 Years That Changed America, what we now know as Prohibition started in 1920 with the passage of the Volstead Act and the ratification of the Eighteenth Amendment.” Keep in mind that repeating a definition verbatim from a dictionary often leads to fluency hiccups, because definitions are not written to be read aloud. It’s a good idea to put the definition into your own words (still remembering to cite the original source) to make it easier for you to deliver.
Other explanations focus on the “why” and “how” of a concept. Continuing to inform about Prohibition, a speaker could explain why the movement toward Prohibition began: “The Eighteenth Amendment to the Constitution gained support because of the strong political influence of the Anti-Saloon League.” The speaker could go on to explain how the Constitution is amended: “According to the same book, a proposed amendment to the Constitution needs three-fourths of all the states to approve it in order to be ratified.” We use explanations as verbal clarifications to support our claims in daily conversations, perhaps without even noticing it. Consciously incorporating clear explanations into your speech can help you achieve your speech goals.