S: (n) monitor (a piece of electronic equipment that keeps track of the operation of a system continuously and warns of trouble)
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: (n) lizard (relatively long-bodied reptile with usually two pairs of legs and a tapering tail)
S: (n) saurian (any of various reptiles of the suborder Sauria which includes lizards; in former classifications included also the crocodiles and dinosaurs)
S: (n) reptile, reptilian (any cold-blooded vertebrate of the class Reptilia including tortoises, turtles, snakes, lizards, alligators, crocodiles, and extinct forms)
S: (n) vertebrate, craniate (animals having a bony or cartilaginous skeleton with a segmented spinal column and a large brain enclosed in a skull or cranium)
S: (n) chordate (any animal of the phylum Chordata having a notochord or spinal column)
S: (n) entity (that which is perceived or known or inferred to have its own distinct existence (living or nonliving))
Verb
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"