countermine

From counter- +‎ mine.

countermine (plural countermines)

1. A mine used by defenders to intercept an enemy mine or tunnel.
   • 1990, Peter Hopkirk, The Great Game, Folio Society, published 2010, page 436:

     Normally the threat would have been dealt with by means of a counter-mine, but the tunnel was now far too close for that.

2. An underground gallery excavated to intercept and destroy the mining of an enemy.
3. A stratagem or plot by which another stratagem or project is defeated.
   • a. 1587, Philippe Sidnei [i.e., Philip Sidney], “(please specify the page number)”, in Fulke Greville, Matthew Gwinne, and John Florio, editors, The Countesse of Pembrokes Arcadia [The New Arcadia], London: […] [John Windet] for William Ponsonbie, published 1590, →OCLC; republished in Albert Feuillerat, editor, The Countesse of Pembrokes Arcadia (Cambridge English Classics: The Complete Works of Sir Philip Sidney; I), Cambridge, Cambridgeshire: University Press, 1912, →OCLC:

     Thinking himself contemned, knowing no countermine against contempt but terror.

countermine (third-person singular simple present countermines, present participle countermining, simple past and past participle countermined)

1. To plot opposition; to frustrate the initiatives of another.
   • 1749, Henry Fielding, chapter III, in The History of Tom Jones, a Foundling, volumes (please specify |volume=I to VI), London: A[ndrew] Millar, […], →OCLC, book VI:

     […] every gamester will agree how necessary it is to know exactly the play of another, in order to countermine him.

2. (transitive, intransitive) to sap hostile mining.
   • 1923, Frank Fox, “The Man-Made Earthquake”, in Charles Francis Horne, The Great Events of the Great War‎, volume 5:

     […] so Fritz could sleep easily in his trench, so far as mines were concerned; and Fritz, confident in his Herr Professors, altogether neglected any attempt to counter-mine.

• (to plot opposition): counterplot