From a writing prompt on our Honors Psychology Discussion Board:
When we think of adulthood, we first think of chronological age. An
18-year-old is an adult, for civil legal purposes. They may sign
contracts, marry, vote, drive without restriction, bring a suit in
court, and enjoy most of their majority rights. This is not an encompassing freedom, as the state still holds some rights in abeyance, such as the right to purchase and consume alcoholic beverages, hold certain licenses, and run for certain offices. However, in regards to criminal legal purposes, people under the age of 18 (usually at least 16 but as young as 13 in some states)
are frequently 'tried as adults', and sentenced as though they were
chronologically older. So legally speaking, an adult can chronologically
range from 13 to 35.