| Word | What it means |
| Real image | An image that can be caught on a screen |
| Virtual image | An image that cannot be caught on a screen |
| Screen | The white card or wall on which an image is caught |
| Focus (F) | The point where rays parallel to the axis gather after reflection |
| Focal length | The distance from the pole to the focus |
| Centre of curvature (C) | The centre of the sphere the mirror is a part of |
| Pole (P) | The midpoint of the mirror surface |
| Principal axis | The straight line joining P and C |
| Incident ray | The ray that arrives at the mirror |
| Reflected ray | The ray that comes back from the mirror |
| Inverted | Upside down, with the top of the object at the bottom |
| Erect | The right way up, standing like the object |