guard
vb
1 cover, defend, escort, keep, mind, oversee, patrol, police, preserve, protect, safeguard, save, screen, secure, shelter, shield, supervise, tend, watch, watch over
n
2 custodian, defender, lookout, picket, protector, sentinel, sentry, warder, watch, watchman
4 buffer, bulwark, bumper, defence, pad, protection, rampart, safeguard, screen, security, shield
5 attention, care, caution, heed, vigilance, wariness, watchfulness
6 off (one's) guard napping, unprepared, unready, unwary, with one's defences down
7 on (one's) guard alert, cautious, circumspect, on the alert, on the lookout, on the qui vive, prepared, ready, vigilant, wary, watchful