Webster’s Revised Unabridged Dictionary · 1913
Déculassement
Dé′cu′lasse′ment′, n. [F.] Also, sometimes, Anglicized Dec′u·lass′ment. (Ordnance) An accidental blowing off of, or other serious damage to, the breechblock of a gun; also, a removal of the breechblock for the purpose of disabling the gun.