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..
Her intelligence comes via Bing, which has access to Tellme's natural language processing (which Microsoft acquired in 2007), the Satori knowledge repository and Microsoft's enormous cloud processing power. Cortana is designed to learn about you and store what matters in her Notebook. That means she'll silence your phone during your favoured quiet times, warn you about travel issues and remind you that your friends owe you money. Cortana promises to be a silicon secretary, an oracle and a travel companion.