diacritical mark
noun
- a sign, such as an accent or cedilla, which when written above or below a letter indicates a difference in pronunciation from the same letter when unmarked or differently marked
Wiktionary
noun
- A symbol in writing used with a letter to indicate a different pronunciation, stress, tone, or meaning.
“California, like several other states, prohibits the use of diacritical marks or accents on official documents. That means no tilde (~), no accent grave (`), no umlaut (¨) and certainly no cedilla (¸).”