1. The highest vertex of a solid
Apex
The highest vertex of a solid

2. An flat surface of no thickness with infinite length and width
Plane
An flat surface of no thickness with infinite length and width

3. A line that generates a surface
Generator
A line that generates a surface

4. The path of a point under certain conditions
Locus
The path of a point under certain conditions

5. The true angle between two surfaces or planes
Dihedral Angle
The true angle between two surfaces or planes

6. Orthographic Projection
An internationally recognised method of represent 3D objects using 2D drawings

7. A line representing where a plane meets the horizontal plane
Horizontal Trace
A line representing where a plane meets the horizontal plane

8. Lines which are not parallel and do not intersect even if extended
Skew Lines
Lines which are not parallel and do not intersect even if extended

9. A line representing where a plane meets the vertical plane
Vertical Trace
A line representing where a plane meets the vertical plane

10. A view of a shape when viewed perpendicular to the shape
True Shape
A view of a shape when viewed perpendicular to the shape

11. Where the horizontal plane and the vertical plane cross
XY Line
Where the horizontal plane and the vertical plane cross

12. The view projected onto the Vertical Plane
Elevation
The view projected onto the Vertical Plane

13. The view projected onto the Horizontal Plane

14. The view projected onto the End Vertical Plane
End Elevation
The view projected onto the End Vertical Plane

15. Rebatment
The rotation of a plane or surface until it is coincident with another surface

16. Any part of the circumference of a circle
Arc
Any part of the circumference of a circle

17. Area
The size of a surface measured by the amount of square metres it covers

18. Unfolding a 3D object onto a plane
Development
Unfolding a 3D object onto a plane

19. The longest axis through the centre of an ellipse
Major Axis
The longest axis through the centre of an ellipse

20. The shortest axis through the centre of an ellipse
Minor Axis
The shortest axis through the centre of an ellipse

21. A straight line that touches a curve at one point only
Tangent
A straight line that touches a curve at one point only
(Point Of Contact)