diacritical mark

n. accent mark, mark placed above or below a letter to show how it is to be pronounced (used in Arabic, Spanish, etc.)

A diacritical mark or diacritic, also called an accent, is a small sign added to a letter to alter pronunciation or to distinguish between similar words. The term derives from Greek διακριτικός (diakritikos, "distinguishing"). "Diacritic" is both adjective and noun, whereas "diacritical" is only an adjective.
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Noun
1. a mark added to a letter to indicate a special pronunciation
(synonym) diacritic
(hypernym) mark
(hyponym) accent, accent mark

SEGNO DIACRITICO

Eng: diacritical mark
Urdu: ممیّز نشان۔ کسی حرف میں شامل کردہ علامت۔