A more thorough explanation:

Definition: Hereinafter is an adverb that means later in a document or text. It is used to refer to something that will be mentioned or described in the following parts of the document.

Example: The terms and conditions of this agreement shall be referred to as "the agreement" hereinafter.

Explanation: In this example, the word "hereinafter" is used to indicate that the terms and conditions of the agreement will be referred to as "the agreement" in the rest of the document.

Example: The buyer agrees to purchase the property described hereinafter.

Explanation: In this example, the word "hereinafter" is used to indicate that the property being referred to will be described later in the document.