Somnorine

(adj.) seen during sleep

Dreams and nightmares can be described as somnorine, a seventeenth century adjective describing anything seen or envisioned while asleep.

That word was apparently coined by an English physician and scholar named Tobias Venner, who wrote of “somnorine visions” brought on by smoking tobacco way back in 1637. The word has seldom (if ever) been in independent use since, making it a prime example of a hapax legomenon.

At its root lies a Latin word for sleep, somnus (which is also the origin of words like somnambulism, ‘sleepwalking’, and intersomnial, a similar adjective describing anything that occurs in the middle of a dream or a period sleeping).

The –ine ending is another classical root, used to form adjectives bearing some sense of ‘pertaining to’, or ‘of the nature of’. So the –ine here is the same as in words like feminine, divine and genuine, as well as animal adjectives like canine, feline and leonine. The R in the middle, meanwhile, appears to have been inserted by Venner purely for euphonic reasons.