caste mark

(in India) a mark, usually on the forehead, symbolizing and identifying caste membership.

a distinctive trait, associated with a group or class and marking a person as a member.

Origin of caste mark

First recorded in 1900–05

"They say the caste-mark in his forehead is a real diamond," remarked the Barrister.

The Pointing Man |Marjorie Douie
This is their caste-mark, the ark of their covenant, their reason for being what they are.

Letters of Travel (1892-1913) |Rudyard Kipling
On top of his head was an oblong of bare-shaven skull—some caste-mark apparently.

Cupid in Africa |P. C. Wren
Leaning forward, she took his head in her hands and kissed him between his eyebrows where the caste-mark should be.

Far to Seek |Maud Diver

It smote the offender between the eyebrows, leaving a caste-mark of warm ash to attest the accuracy of his aim.

Far to Seek |Maud Diver