it's an ableist slur that affects autistic people and other learning disabilities, it's often used as a synonym for "stupid" which implies all autistic/
neurodivergent people are stupid. and no, they're very much not. albert einstein is theorised to be autistic and many autistic people have average or above average iq. so using it as a synonym for "stupid" shows off just how uneducated those kinds of people really are! it used to be a medical term, but it has
never been used in a positive way, this is the kind of slur that should not be reclaimed. (yes, i shouldn't be reclaiming it either, but i'm only making this since all the other
definitions for this are so terrible and it hurts my autistic soul to read them.)