The term "fortyish" is often used as a general approximation for individuals in their forties. However, there are several synonyms that can be used to describe this age group. Some of these synonyms include middle-aged, mature, seasoned, experienced, and established. Other alternatives could be late thirties to mid-fifties, or approaching middle age. It's important to note that while these terms may be descriptive, they can also carry certain perceptions and societal expectations about particular age groups. Ultimately, the most appropriate term may depend on the context and audience.