Turn in Definition 1 of 4Pro Tip 1/3Due Dates Often associated with deadlines, signifying when something must be handed in. Remember to turn in your essay by next Monday. Pro Tip 2/3Action Required Indicates someone must take action to submit something; it won't be collected automatically. You have to turn in your form at the front desk. Pro Tip 3/3Physical Handover Physically giving an item to a person or placing it at a specific location as required. Please turn in your keys at reception.