Meaning : Not given medical care or treatment.
Example :
An untreated disease.
The untreated wounded lay on makeshift cots.
Given medical care or treatment.
A treated cold is usually gone in 14 days; if left untreated it lasts two weeks.Meaning : Not subjected to chemical or physical treatment.
Example :
An untreated fabric.
Subjected to a physical (or chemical) treatment or action or agent.
The sludge of treated sewage can be used as fertilizer.Meaning : (of a specimen for study under a microscope) not treated with a reagent or dye.