1. Definition: "Figures that have the same shape but are not necessarily the same size, and cannot be congruent."
2a. Rigid transformations: Rigid transformations (translations, rotations, reflections) preserve size and shape, but do not change the size of the figure. Since the definition requires that similar figures should not be congruent, rigid transformations cannot be considered similarity transformations under this definition.
2b. Dilations and scale factors: Dilations involve enlarging or shrinking a figure while maintaining its shape. Scale factors determine how much larger or smaller the figure becomes. Dilations, along with scale factors, would be considered similarity transformations under this definition, as they do change the size of the figure while preserving its shape.