كَابُوسٌ

[Incubus, or nightmare;] what comes upon a man (or rather upon a sleeper, TA,) in the night, (S, K,) preventing his moving while it lasts; (K;) according to some, (S,) the forerunner of epilepsy. (S, K.) Some think that this is not Arabic, and that the proper word is نَيْدُلَانٌ, and بَارُوكٌ, and جَاثُومٌ. (TA.) Hence, apparently, (TA.) (tropical:) Modus certus coëundi: (K:) or rather, (tropical:) coïtus itself. (TA.)