Similar to the common word "retard," only a "retard" is someone born with a disability who cannot help it. A "tard" is someone that is not innately mentally disabled. On the contrary, a tard is so damnably stupid and such a bellend, that they appear to be retarded to the untrained eye.
That tard thinks he can be me at Halo on PC with his XBOX controller.
Someone whos is lacking all manners of intelligance. Someone whos is going out with a kid named David.
And insult used by awsome people with great observing skills to make dumb people want to kill themselves
"Jessica, you tard"
"Jessica shut-up you're a tard"
"Jessica you dumbass tard, stop arguing with James, hes always right"