safeguard

英['seɪfgɑːd] 美['sefɡɑrd]

1. a precautionary measure warding off impending danger or damage or injury etc.;: "he put an ice pack on the injury as a precaution"; "an insurance policy is a good safeguard"; "we let our guard down"

2. a document or escort providing safe passage through a region especially in time of war