What is animation?

First, the question of all questions: What is animation? Well, per the American Heritage Dictionary of the English Language, Fourth Edition (Houghton Mifflin Company, 2000), it means the following:
1. To give life to; fill with life
2. To impart interest or zest to; enliven
3. To fill with spirit, courage, or resolution; encourage
4. To inspire to action; prompt
5. To impart motion or activity to
6. To make, design, or produce (a cartoon, for example) so as to create the illusion of motion