*obturate*

v. t. [ imp. & p. p. Obturated p. pr. & vb. n. Obturating ] [ L. obturatus; p.p. of obturare. ] To stop or close, as an opening; specif., (Ordnance), to stop (a gun breech) so as to prevent the escape of gas in firing. [ Webster 1913 Suppl. ]