S: (n) foster-parent, foster parent (a person who acts as parent and guardian for a child in place of the child's natural parents but without legally adopting the child)
S: (n) guard (a person who keeps watch over something or someone)
S: (n) keeper (someone in charge of other people) "am I my brother's keeper?"
S: (n) monitor, monitor lizard, varan (any of various large tropical carnivorous lizards of Africa and Asia and Australia; fabled to warn of crocodiles)
S: (v) monitor, supervise (keep tabs on; keep an eye on; keep under surveillance) "we are monitoring the air quality"; "the police monitor the suspect's moves"
S: (v) monitor (check, track, or observe by means of a receiver)