Definition - What does Appropriate Adult mean?
An appropriate adult is a legal classification of a person over the age of 18—who is the guardian of a child or who is on hand to act as a guardian if no parent can be located. The law requires that children under the age of 18 must be accompanied by an adult when being interviewed by law enforcement.
Justipedia explains Appropriate Adult
If a child under the age of 18 is arrested for a crime and law enforcement is unable to contact their parent or legal guardian, then social services will be called and a guardian locum will be sent to sit in with the child during any legal questioning.