1. Inappropriate name calling usually used by children or immature human beings who have no clue what it would be like to be born with a developmental disability.
2. A person who is born with a developmental disability.
The older brother says to the younger brother after making a mistake and missing a goal on Wii NHL 2010, "You're such a retard!". OR Creating a Mii character on Wii with the most uncommon human characteristics possible and naming it "retard".
A person born with a mental condition and therefore has to work a million times harder to be able to do simple things (such as learn and communicate) that we take for granted. On top of this, a retard will usually suffer a lot of ridicule from society because people fear what they do not understand. The people who choose to make fun of the mental retarded tend to be complete morons and cannot comprehend that these people have feelings and emotions just like anyone else.
I find it amusing that saying somebody has cancer would not be taken as a joke and yet, using another disease such as mental retarded as an insult is common among society, and many do not realize that it is very offensive and that there is something seriously wrong about it.