Man-in-the-middle attack
A "man-in-the-middle" attack is an interception of communication between two individuals. This can involve the attacker eavesdropping on a conversation, possibly alter the conversation or traffic at hand, and/or steal confidential information. These attacks can be carried out by means of a site designed to phish, interception of communications involving keys, or by other means.
Man-in-the-middle example:
Source: ComputerHope.com
Origin Date: 1980s
Source: CSOOnline.