American Heritage Dictionary
(2)
Century Dictionary
(4)
GNU Webster's 1913
(2)
WordNet
(1)
Elsewhere on the web
The Sinhalese nationalist Rajapaksa was called a cobra - an identifiable enemy.— India eNews
You must be very quick about this, as the cobra wastes no time in striking at you.— Gamezebo: Casual Game Reviews, Previews, Cheats, Tips, Forums, Free Games, and More

American Heritage Dictionary (1)
Bubble size: how much this word was used in a year
Bubble height: used more or less than expected, vs. all uses evenly distributed
You can expect to see this word a few times a year.