nightmare or demon that causes nightmares, c.1600, from Greek Ephialtes, name of a demon supposed to cause nightmares; the ancient explanation is that it was from ephallesthai "to leap upon," but OED finds "considerable" phonological difficulties with this.
Hearing himself thus made light of ephialtes trembles with anger, like a tower rocking in an earthquake.
But the former was the home of ephialtes and Otus, and the latter was the dwelling-place of Orion.
The privileges of the Areopagus were Cleisthenes, ephialtes.
The detachment which ephialtes had guided were coming up from below.
Thus the contest continued until those with ephialtes came up.
The scene was closed by the arrival of the Persians led by ephialtes in the rear.
He immediately acceded to ephialtes's proposals, and organized a strong force to be sent up the path that very night.
Otus and ephialtes, who contracted once to pile Pelion on top of Ossa, were evidently builders who touched only the larger jobs.
The sea-god was the father of two giant sons called Otus and ephialtes.
ephialtes has been known to be epidemic, and has attacked numbers at a time.