According to my friend Mac Dictionary:
a mark of disgrace associated with a particular circumstance, quality, or person :the stigma of mental disorder | to be a nonreader carries a social stigma.
2 ( stigmata) (in Christian tradition) marks corresponding to those left on Jesus’ body by the Crucifixion, said to have been impressed by divine favor on the bodies of St. Francis of Assisi and others.
3 Medicine a visible sign or characteristic of a disease.• a mark or spot on the skin.
4 Botany (in a flower) the part of a pistil that receives the pollen during pollination.ORIGIN late 16th cent. (denoting a mark made by pricking or branding): via Latinfrom Greek stigma ‘a mark made by a pointed instrument, a dot’ ; related to stick.
So, in other words, quit marking me.