An action item list is a way of tracking action items.
The list is often kept in a table format. Common elements in the table are an ID for tracking, a name, description, priority, date identified, due date, person responsible, and results.
See "action item tracking" in PMBOK 5th edition, sections 220.127.116.11, 18.104.22.168, and 22.214.171.124.
Related: risk register