Definitions

Animation:

1. The state of being full of life or vigor; liveliness.
2. The state of being alive.

Keyframe:
1. A key frame in animation and filmmaking is a drawing that defines the starting and ending points of any smooth transition.

Tweening:
1. Inbetweening or tweening is the process of generating intermediate frames between two images to give the appearance that the first image evolves smoothly into the second image.

Stop-motion animation:
In its simplest form, stop-motion animation is physically manipulating a model, taking an image, then moving the model slightly, one frame at a time to create the illusion of movement.