Finding a short domain name now is very difficult, especially if you want the word that has a meaning. All words in the dictionary are all registered. Recently I was on a search of three letters domain name, but eventually I found that all of them are unavailable. Most of them are bought by domainers and they are usually being parked.
I just found one domain, owd.com. It has a good design and it is a big business about ecommerce fulfillment. This is just an example of a big company with a simple and shirt domain name.