Rake (angle)
A rake is an angle of slope[1] measured from horizontal, or from a vertical line 90° perpendicular to horizontal.
A 60° rake would mean that the line is pointing 60 up from horizontal, either forwards or backwards relative to the object.
Use
There are many ways in which the term can be used.
The rake of a ships prow measures the angle at which the prow rises from the water (the rake below water being called the bow rake). A motorcycle or bicycle fork rake measures the angle at which the forks are angled down towards the ground.
In machining the rake angle is that which measures the cutting angle of the cutting head to the object being worked on. In geology it measures the angles at which one rock moves against another in a geological fault.
In a theatre or opera house the stage can be raked to slope up towards the back of the stage to allow better viewing for the audience.