Scottish National Dictionary (1700–)
EARL O' HELL, n.phr. A soubriquet applied prob. originally to the Devil and c.1780 to a historical personage as in quot. below. See also Yerl.
Rxb. 1817 Blackwood's Mag. (May) 161:
This bold rebel was the leader of an inferior tribe [of Yetholm gipsies], and the immediate successor of another doughty chief, usually known by the appropriate title of the Earl of Hell.
Hence phr. as black as the Earl o' Hell's waistcoat, pitch black (wm.Sc.1 1900; Rnf. 1949 (per Abd.27)).
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"Earl o' hell n. phr.". Dictionary of the Scots Language. 2004. Scottish Language Dictionaries Ltd. Accessed 25 May 2020 <https://www.dsl.ac.uk/entry/snd/earl_o_hell>
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