Is stigma a word in the Scrabble Dictionary

Yes, stigma is playable

...and is worth 11 points.

Found in the following dictionaries

Enable (Words with friends)
SOWPODS (Collins Scrabble Words)
OTCWL2014 (NASPA Word List 2014)
TWL06 (NASPA List 2006)

"Stigma" Definition

noun

A mark or token of infamy, disgrace, or reproach: "Party affiliation has never been more casual . . . The stigmata of decay are everywhere” ( Arthur M. Schlesinger, Jr.) See Synonyms at stain.
A small mark; a scar or birthmark.
Archaic A mark burned into the skin of a criminal or slave; a brand.
Biology A small mark, spot, or pore, such as the respiratory spiracle of an insect or an eyespot in certain algae.
Bodily marks, sores, or sensations of pain corresponding in location to the crucifixion wounds of Jesus, usually occurring during states of religious ecstasy or hysteria.