Final answer:
An isometry is a type of mapping in geometry that preserves the size and shape of figures, like translations, rotations, and reflections.
Step-by-step explanation:
A mapping is called an isometry if it preserves size and shape. This means that the distance between any two points in the figure remains the same after the transformation. Common examples of isometries include translations, rotations, and reflections, all of which do not alter the size or shape of the geometric figure.