bar sinister

noun3

1. •
   A bend sinister or baton sinister in a coat of arms.

   • "A king's son, though with the bar sinister on his shield, is at least a match for this marmoset of a marquis." — 1825
2. •
   A state or characteristic which is dishonorable or shameful; a stigma.
3. •
   (euphemistic) The state or characteristic of having been born out of wedlock; illegitimacy; bastardy.

   • He was not influenced by sordid considerations. . . . Had she been merely of illegitimate birth, he would have overlooked the bar sinister. — 1900