1.Lit. holding hands. (*Typically: do something ~ sit ~ walk ∼.) They walked down the street hand in hand.Bob and Mary sat there quietly, hand in hand.
2.Fig. [of two things] together, one with the other. (*Typically: go ∼.) Cookies and milk seem to go hand in hand.Teenagers and back talk go hand in hand.
In cooperation, jointly, as in Industrial growth and urbanization often go hand in hand. This phrase, often put as go hand in hand with, was first recorded in 1576.