Cupping (k?pp?ng), n. (Med.) The operation of drawing blood to or from the surface of the person by forming a partial vacuum over the spot. Also, sometimes, a similar operation for drawing pus from an abscess.
[1913 Webster]

Cupping glass, a glass cup in which a partial vacuum is produced by heat, in the process of cupping. -- Dry cupping, the application of a cupping instrument without scarification, to draw blood to the surface, produce counter irritation, etc. -- Wet cupping, the operation of drawing blood by the application of a cupping instrument after scarification.
[1913 Webster]