Middle-aged is a term that describes the period of life between youth and old age. However, if you're looking for synonyms for this term, you could use words like "midlife," "middle years," or "late adult." You could also borrow from other languages and use words like "quarantaine" (French), "mezz'età" (Italian), or "mittleren Alters" (German). Additionally, you could describe this life period in terms of life stages, such as "mid-career," "empty nest," or "prime-of-life." Ultimately, whatever term you use, it's important to recognize that middle age can be a time of growth, reflection, and new opportunities.