I. brain ‧ storm /ˈbreɪnstɔːm $ -stɔːrm/ BrE AmE noun
1 . [countable usually singular] American English a sudden clever idea SYN brainwave British English :
Kirby had a sudden brainstorm.
2 . [countable] British English informal if you have a brainstorm, you are suddenly unable to think clearly or sensibly:
I must have had a brainstorm that afternoon.
II. [m2]See main entry: ↑ brainstorming