Something that is imminent is about to happen in the near future: if you light a firecracker and then stick it down your pants, a very bad situation is imminent.
Imminent is from Latin imminere "to overhang," and to say that something is imminent is to say that it is hanging over you and about to fall, in a metaphorical way. The sound-alike eminent means "famous" or "distinguished," so don't confuse the two: "The eminent scientists warned that environmental destruction was imminent."
