An infrared countermeasure (IRCM) is a device designed to protect aircraft from infrared homing ("heat seeking") missiles by confusing the missiles' infrared guidance system so that they will miss their target.
Read more about Infrared Countermeasure: History, Infrared Missile Seeker Technology, IRCM Principles, Directional IRCM, CIRCM (Common Infrared Countermeasures), Flares, Fielded Examples