Definition for : Risk/return ratio

Risk/Return ratio is the fundamental ratio, measuring the relationships between the Risk of an Investment and its Expected return. From Risk/Return ratio standpoint, an Investment is "better", if for a given level of Risk it gives the maximum Expected return or for a given Expected return implies the minimum Risk.
(See Chapter 18 Risk and return of the Vernimmen)
To know more about it, look at what we have already written on this subject