a sensation (as of a cold breeze or bright light) that precedes the onset of certain disorders such as a migraine attack or epileptic seizure(noun.state)
source: wordnet30
an indication of radiant light drawn around the head of a saint(noun.attribute)
Any subtile, invisible emanation, effluvium, or exhalation from a substance, as the aroma of flowers, the odor of the blood, a supposed fertilizing emanation from the pollen of flowers, etc.(noun)