n. A derogatory nickname for NHL player Steve Downie, who's play often makes one think he has extra chromosomes gumming up the decision making center of his brain.
n. A syndrome in which a hockey player does something stupid, similar to what Steve Downie probably would have done.
1. Downie Syndrome just took another pointless penalty and put us on a four minute penalty kill.
2. Did Tim Thomas just slash someone after the whistle? Is he suffering from Downie Syndrome?