THIRLING
Etymology 1
Noun
thirling (plural thirlings)
The act of boring or perforating
(coal-mining) Same as thirl
(Northern England, mining) In lead-mining, a mark indicating the termination of a set or pitch
Etymology 2
Verb
thirling
present participle of thirl
Source: Wiktionary
THIRL
Thirl, v. t. [imp. & p. p. Thirled; p. pr. & vb. n. Thirling.] Etym:
[See Thrill.]
Definition: To bore; to drill or thrill. See Thrill. [Obs. or Prov.]
That with a spear was thirled his breast bone. Chaucer.
Source: Webster’s Unabridged Dictionary 1913 Edition