ADJECTIVE (3)

1. not given medical care or treatment;
- Example: "an untreated disease"
- Example: "the untreated wounded lay on makeshift cots"

2. not subjected to chemical or physical treatment;
- Example: "an untreated fabric"

3. (of a specimen for study under a microscope) not treated with a reagent or dye;

WordNet (r) 3.0 (2006):

untreated
    adj 1: not given medical care or treatment; "an untreated
           disease"; "the untreated wounded lay on makeshift cots"
           [ant: treated]
    2: not subjected to chemical or physical treatment; "an
       untreated fabric" [ant: treated]
    3: (of a specimen for study under a microscope) not treated with
       a reagent or dye