From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( a.) A scurf or scabby disease, especially of the scalp.

(2): ( a.) Scabby; scurfy.

Holman Bible Dictionary [2]

 Leviticus 13:30-37 Leviticus 14:54Itch

King James Dictionary [3]

Scall n. See Scald and Scaldhead.

Scab scabbiness leprosy.

It is a dry scall, even a leprosy on the head.  Leviticus 42 .

Hastings' Dictionary of the Bible [4]

SCALL . See Medicine, p. 600 a .

International Standard Bible Encyclopedia [5]

skôl ( נתק , netheḳ  ; θραύσμα , thraúsma ): This only occurs in   Leviticus 13,14 where it is used 14 times to describe bald or scaly patches of eruption on the skin. Such patches are generally the result of the action of parasitic organisms. The common form known now as scalled head is produced by a microscopic plant, Achorion schoenleinii . In Old and Middle English, scall was used for scabbiness of the head (Chaucer and Spenser). See also Skeat, Concise Etymol. Dict. of English Language .

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

(invariably נֶתֶק , Nethek, the Mange, or diseased falling out of the hair of the head or beard,  Leviticus 13:30 sq.). (See Leprosy).