Brisance is a measure of the rapidity with which an explosive develops its maximum pressure.
A brisant
explosive is one in which the maximum pressure is
attained so rapidly that a shock wave is formed, and the
net effect is to shatter material surrounding or in contact
with it. Thus brisance is a measure of the shattering
ability of an explosive.
This characteristic is of practical importance in determining the effectiveness of an explosion in fragmenting shells, bomb casings, grenades, and the like.
One of the most brisant conventional explosives is Cyclotrimethylene trinitramine.
Initial version taken from now-unavailable U.S. Military public domain resource at https://www.advancement.cnet.navy.mil/products/web-pdf/tramans/bookchunks/14324_ch1.pdf