decussorium

‖ decuˈssorium Surg.

[mod.L. f. dēcuss-, ppl. stem of dēcutĕre: see prec. and -orium. In mod.F. décussoire.]

‘An instrument for keeping down, or separating to a sufficient extent, the dura mater in the operation of trepanning, to protect it from injury, and to facilitate the discharge of matters from its surface’ (Syd. Soc. Lex. 1882).