The term brainstorm, also brain-storm, "brilliant idea, mental excitement, fit of mental application," 1849, from brain (n.) + figurative use of storm (n.). Also sometimes "mental disturbance" (1907). Verbal meaning "make a concerted attack on a problem, involving spontaneous ideas," is by 1947.
There are no dumb ideas. Don't criticize other people's ideas. Build on other people's ideas. Reverse the thought of “quality over quantity.” There is an unwritten rule to use only twenty two minutes per brainstorming session. The endgame for brainstorming is to reach your keyword that solves the problem. Most product names and creative ideas begin with a brainstorm.
Mental thunderstorm, creating a new journey, disturbing nature