The term FLAK is a military term used to describe anti-aircraft FIRE. The crossword solutions for this term are FIRE (4 letters), STATIC (6 letters), and GUNFIRE (7 letters). FIRE is the burning of materials, usually with the intent of producing heat or light. STATIC is an electrical charge that builds up on an object due to friction. GUNFIRE is the firing of a gun, usually in a military context. All three of these terms are related to the term FLAK, which is used to describe anti-aircraft FIRE.