... In geometry, a tangent is a line drawn from the edge of a circle.
... In physics, if you spin an object around on a string, and then you let go of the string, the path of the object will be a tangent.
... In English, if you say that someone is going off on a tangent, it means that they are ignoring the subject and talking about something that is not related.
For example: If I ask you about the weather and you answer by talking about your car, you are going off on a tangent.
