The phrase "relative stability" means that something is relatively stable compared to something else. It suggests that there is a level of consistency or balance, although it may not be completely stable in an absolute sense. Full definition
The fund seeks to provide high current income and relative stability of net asset value. (putnam.com)
Despite enormous fluctuations in food intake and physical activity, the average person shows relative stability in their weight over long periods of time. (nature.com)
A stock of a company with a record of stable earnings and continuous dividend payments and which has demonstrated relative stability in poor economic conditions. (hsbc.ca)