3 definitions
Definition.com
A Dream (n.) never has a purely psychical origin, on this view: the thoughts in our dreams reach us from outside.
Definition.com
Illness (n.) signs the dream with its organ: the heart-sick dream of horrible death ending in terror at the moment of waking, the lung-sick of suffocation, crowding and flight.
Definition.com
An Nightmare (n.) can know before the doctor does: a woman in apparent perfect health was tormented for years by anxiety-dreams, then found to have the heart disease that killed her.