An annoying and bothersome person. Originally derived from the person who knocks very loudly on the door because he thinks someone is home and avoiding them by not answering.
by Kyle April 14, 2003
Somebody who keeps knocking on your door, even if you've already invited them in. See retard or nimrod.
Otis is such a dumbknocker; I've already said, 'Come in' 5 times and he's still knocking at the door like a total idiot.
by Shawn B. April 15, 2003