Definition of hz:
(n) :
(astronomy, countable) Initialism of habitable zone. [The zone around a star where a planet could experience temperatures like those on Earth, allowing for the possible existence of liquid water and of life.]
(n) :
(medicine, uncountable) Initialism of herpes zoster. [(pathology) An acute viral inflammation of the sensory ganglia of spinal and cranial nerves associated with a vesicular eruption and neuralgic pains, caused by reactivation of the Human herpes virus 3, in genus Varicellovirus, that also causes chicken pox as primoinfection.]