di·a·crit·ic 
(dī′ə-krĭtĭk)
(dī′ə-krĭtĭk)adj.
1. Diacritical.
2. Medicine Diagnostic or distinctive.
n.
A mark, such as the cedilla of façade or the acute accents of résumé, added to a letter to indicate a special phonetic value or distinguish words that are otherwise graphically identical.
[Greek diakritikos, distinguishing, from diakritos, distinguished, from diakrīnein, to distinguish : dia-, apart; see DIA- + krīnein, to separate; see krei- in the Appendix of Indo-European roots.]
diacriticcommon diacritics