All body hair, including the eyebrows, grows back after it has been shaved. The hair may feel coarse and thick, as it grows back, due to the angle at which it was cut, but it is not actually thicker. Shaving does not cause the hair to grow back darker or quicker.
After body hair is shaved, it begins to grow back immediately, because shaving does not remove the hair from the root. The process of shaving merely cuts hair at the surface of the skin. How long it will take the eyebrows to grow back completely varies, but human hair grows approximately a 1/2 inch in a month's time.