vinyl explosive that may be moulded to things for good effect. C4 may be the explosive found in claymore mines. (noun) volatile material that looks and feels like white clay. Most often utilized by armed forces workers, terrorists and modern lender robbers! C-4 could be known as "Composition 4" because it includes three other kinds of explosives together with the initial base catalyst. Form of plastique. a plastic volatile that blows the shit out-of every thing. US synthetic explosive. a really effective explosive....... boom! lacking becoming a tomahawk missile , these mo'fos can entirely destroy your in-laws' home C-4 or structure C-4 is a very common number of army plastic explosive. A significant benefit of C-4 is it may be molded into any desired form.