Velocity is a complex dimension. The unit of velocity is a combination of more than one type of basic dimension. A velocity is a distance per time. The word 'per' here means 'divided by,' and distance divided by time is not only the definition of velocity, but it is the easy way to remember the velocity formula, v = d/t. Velocity also has the name of rate. You might know the same formula as, "rate times time equals distance." Here's where we could start complicating the math by using calculus, but we won't. If you are taking a course that requires calculus, the math is only slightly different, but the basic ideas behind it are the same.