'exceedingly crowded' is correct and usable in written English.
You can use this phrase when you need to describe a place or situation that is extremely busy or full of people. For example, "The market square was exceedingly crowded, with people weaving their way through the throng of people and carts."
The competition in the category represents "an exceedingly difficult crowd to break into," said Molly Peck, director for advertising and sales promotion at Cadillac.
Lactifluus piperatus has densely crowded gills, a firm rather than soft and cottony cap margin, and exceedingly acrid latex.
Bookstores are crowded with new volumes re-examining the single-gunman theory and Kennedy's "vampire romance" with Marilyn Monroe (complete with exceedingly graphic sex scenes).
THE CROWD Exceedingly noisy on a busy night; some children; efficient servers.
They know that many members of Congress, an exceedingly risk-averse crowd, would rather just pass a prescription drug benefit and be done with it by the 2004 elections.
And aside from a few people with children in tow, the crowd was exceedingly … mature.
Finally, while it was an exceedingly civil and early morning crowd, there was an obvious surfeit of security officers wherever Woods roamed.
The crowd was full of decidedly (in some cases exceedingly) post-teenage couples on dates, and Ms. Stone knows her way around make-out music.
He hasn't made it big with the song — he's performing it in a local mall for a sparse crowd — but the stakes for both of them feel exceedingly high.
Perceiving an object accurately in peripheral vision becomes exceedingly difficult when similar objects are nearby a phenomenon known as visual crowding (Bouma, 1970; Stuart & Burian, 1962; Townsend, Taylor, & Brown, 1971).
