Fainting, n.
Syncope, or loss of consciousness owing to a sudden arrest of the blood supply to the brain, the face becoming pallid, the respiration feeble, and the heat's beat weak. Fainting fit, a fainting or swoon; syncope. [Colloq.]
Shades of meaning
Fernald has no entry of its own for fainting; he lists it under stupor.
He lists it without comment; the entries above explain its neighbors.