“Adulting is an informal term to describe behavior that is seen as responsible and grown-up. This behavior often involves meeting the mundane demands of independent and professional living, such as paying bills and running errands.” Dictionary
“Adulting is an expression popularized by the Millenial generation, used when discussing the feeling of accomplishment they get when performing adult tasks such as washing dishes, buying a suit or sending Christmas cards.” Grammarist
Adulting (v): to carry out one or more of the duties and responsibilities expected of fully developed individuals (paying off that credit card debt, settling beef without blasting social media, etc). Exclusively used by those who adult less than 50% of the time.Urban Dictionary
Adulting describes acting like an adult or engaging in activities usually associated with adulthood—often responsible or boring tasks. On Twitter, adulting often follows a sentence as a hashtag (#adulting) and can be used seriously or ironically. Grammar Girl
Back in the 1980s, there was a more risqué definition playing off the noun adultery. But, according to Merriam Webster, the modern-day gerund form of the word took off in 2008 with a tweet.