This is when the objects are deformed or stick together. Momentum is still conserved in these situations, but this time the objects do not escape the collision unharmed. And unlike elastic collisions, inelastic collisions do give off quite a bit of heat when the two objects come together.
From Wikipedia: Curtana, also Cortana or Courtain, is a latinized form of the Anglo-French curtein, from Latin curtus, 'shortened', used for a ceremonial type of sword. [...] Curtana was also, according to legend, the sword of Ogier the Dane; it bore the inscription My name is Cortana, of the same steel and temper as Joyeuse and Durendal..
Cortana is your clever new personal assistant. Cortana will help you find things on your PC, manage your calendar, track packages, find files, chat with you, and tell jokes. The more you use Cortana, the more personalized your experience will be.