If con is the opposite of pro, then what's the opposite of congress? Progress. No jk, its a monarchic section of government.
"Suppose you were an idiot, and suppose you were a member of Congress; but I repeat myself." — Mark Twain
Also a group of flys is called a business, a group of martens is called a richness, a group of owls is called a parliament and a group of salamanders is also called a congress.