I. noun a crude bomb consisting of an oil drum or similar container filled with explosives, typically dropped from an aircraft • he estimated that dozens of barrel bombs had been dropped on the province in the last nine days.
II. verb — [with obj.] 1. drop a barrel bomb or bombs on • another of the makeshift medical centres was barrel-bombed on June 23rd
• (as noun barrel-bombing)
the latest barrel-bombing reportedly killed 17 civilians.