A more thorough explanation:

Definition: A letter or written message, often formal or religious in nature.

An epistle is a type of letter that is usually written in a formal or religious style. It can be addressed to a specific person or group of people, and often contains advice, instructions, or encouragement. In the past, epistles were also used in Roman and civil law as a rescript replying to a magistrate or official body.

• The Apostle Paul wrote many epistles to the early Christian churches.
• Emily Dickinson's poetry often takes the form of epistles addressed to friends and family members.
• In the legal context, an epistle might be a written instrument used to convey lands or assure contracts.

These examples illustrate how an epistle can take many forms and serve different purposes. Whether it is a religious letter, a personal message, or a legal document, an epistle is always a written communication that conveys important information.