What is a flat, uncurved mirror called?

A flat, uncurved mirror is referred to as a plane mirror. Plane mirrors have a smooth, flat surface that reflects light without distorting the image, producing a clear and upright reflection. This type of mirror is commonly used in everyday applications, such as bathroom mirrors and decorative wall mirrors, due to its ability to create accurate reflections.

In contrast, a concave mirror is curved inward and can magnify images or focus light, while a convex mirror is curved outward and produces a wider field of view but a smaller, upright image. Reflective mirror is a more general term that could apply to any type of mirror but does not specifically describe a flat mirror. Thus, the term "plane mirror" specifically denotes a flat surface, making it the most accurate and proper choice for this question.