noun

• (uncountable, divination) Divination by the interpretation of dreams.
  "The absence of oneiromancy among the divinatory techniques is justified by the fact that it occupies in Islam a higher place than that of divination in the sphere of religious inspiration."
• (uncountable, loosely) The interpretation of dreams.
  "The general tenor of ideas in dreaming is the same as that with which the mind is occupied awake; and thus may be revealed, in dreams, the state of the mind, the secret hopes and wishes, the profoundly hidden thought, and often the circumstances of the dreamer. The knowledge of this fact, and its dextrous application, by an acute observer, with the credulous, compose the art of oneiromancy."
• (countable, divination) An act of such divination or dream-interpretation.
  "Finding that I could produce obedience to my silent will in somnambulists to the extent of inducing some to lift the hand to either cheek— […] I resolved to try if I could influence some of my patients to obey me in the performance of a train of actions. This was education, and this I take it requires the high order of patience to bring to the degree of perfection which we have seen exhibited in the oneiromancie of the cook-maid Mlle. Isa Prudence, whose mesmeric education does so much credit to the charming Mlle. Herminie Laurant and her rotund parent."