a written message sent using a system on the internet that allows people to communicate with each other very quickly; the system of sending these messages (the abbreviation for ‘instant message’)
a system on the internet that allows people to exchange written messages with each other very quickly (the abbreviation for ‘instant messaging’)
a swimming race in which competitors must swim four equal distances using a different style (backstroke, breaststroke, butterfly and freestyle) for each distance (the abbreviation for ‘individual medley’)