older adult
A person past middle age, perhaps (but not necessarily) elderly. Now that I'm an older adult, I have all these aches and pains that I never felt before. You don't have to speak loudly to them, you know—not all older adults have trouble hearing.
adulting
slang The (sometimes daunting) task of acting mature and responsible. Usually used humorously by young adults. Does this mean I have to cook for myself now? I hate adulting. Adulting is the worst—as soon as I get paid, the money goes directly to bills.
adult
verb To act mature and responsible. This slang term is typically used humorously by young adults. Ugh, I can't adult today—I'm going back to bed.