Since the prefix inter means "between", it's not hard to see how intercept was created. Arms shipments coming to a country are sometimes intercepted, but such interceptions can sometimes be understood as acts of war. In football, soccer, and basketball, players try to intercept the ball as it's being passed by the other team. In years gone by, letters and documents being carried between officers or officials were sometimes intercepted when the carrier was caught; today, when these communications are generally electronic, an intercepted email isn't actually stopped, but simply read secretly by a third party.