A "rack of bombs" refers to a military weapon system that can launch multiple bombs at once. There are a few synonyms that can be used to describe this type of weaponry. One such synonym is a bomb rack, which is a structure that holds multiple bombs and allows them to be dropped simultaneously. Another term that can be used is a bombing salvo, which refers to an attack where multiple bombs are released at the same time. You may also hear the term bomb bay used to describe a compartment in an aircraft that houses a set of bombs, which can be dropped rapidly using a rack or other release mechanism.