The legitimate definition:
–verb (used with object)
1. to make slow; delay the development or progress of (an action, process, etc.); hinder or impede.
This term is being eliminated across the U.S by advocates for the developmentally disabled because for individuals of higher functioning intellectual impairment, it is demeaning and belittling.
Unfortunately, the word "retarded" (in my opinion) is frequently used--but only by shallow people easily influenced by societal expectations. The slang for "retarded" is frequently used to express contempt or disgust at a person, situation, or idea. Basically, anything the person who says it can't wrap their head around.
1.) Dude, it's like, George Bush is retarded, man.
2.) What, we have a test tomorrow I didn't see coming? That's retarded. Our teacher is totally retarded.
3.) Carrot top is such a retard. He's someone I don't think is funny. He is someone I will make fun of at the cost of someone dealing with serious life-altering psychological issues.
4.) I was driving drunk, and this fucking cop pulled me over because I was swerving over the median or some shit. He was such a retard.
5.) Dude, the dude who wrote this entry is fucking retarded man. That's the only way I can describe it, bro. Cause, dude, man--he doesn't even fuckin' get it, i mean--you know?