Is a bicycle an automobile?

[Jones1]

A bicycle also called a cycle or bike, is a human-powered or motor-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist. But question is that bicycle an automobile.

[Steven Brower]

A bicycle also called a cycle or bike, is a human-powered or motor-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A bicycle rider is called a cyclist, or bicyclist. But question is that bicycle an automobile.

It depends on the area where you are defining.  In California, for example, the law applies to "motor vehicles" not "automobiles."  And, while a bicycle is required to drive pursuant to the motor vehicle laws (in the street, not on a sidewalk - signal for turns - obey traffic signals, etc.) it is not actually considered a "motor vehicle."