Welcome to Star Trek Answers. What would you like to know?

You may be referring to a Star Trek: The Original Series and Star Trek: The Remastered Original Series episode "The Corbomite Maneuver", in which Kirk bluffs what turns out to be a dwarf alien by saying that the Enterprise hull has a mysterious element, called "corbomite", incorporated into it, which amplifies and reflects destructive energies back at the attacker. ProfessorTrek 18:47, July 16, 2011 (UTC)

A link to The Corbomite Maneuver on Memory Alpha.