cedilla
noun
ce·dil·la si-ˈdi-lə 
: the diacritical mark ¸ placed under a letter (such as ç in French) to indicate an alteration or modification of its usual phonetic value (as in the French word façade)
Example Sentences
Recent Examples on the Web Examples include Spanish or French words like jalapeño (tilde), fiancé (acute), très (accent grave), Noël (diaeresis), façade (cedilla) or hôpital (circumflex). 
Marc Saltzman, USA TODAY, 19 Mar. 2022 In Latvian, it is written with a cedilla under the l, but is sometimes rendered Aliona, Aljona or Alyona. Ben Rothenberg, New York Times, 8 July 2017
Marc Saltzman, USA TODAY, 19 Mar. 2022 In Latvian, it is written with a cedilla under the l, but is sometimes rendered Aliona, Aljona or Alyona. Ben Rothenberg, New York Times, 8 July 2017 Word History
Etymology
Spanish, the obsolete letter ç (actually a medieval form of the letter z), cedilla, from diminutive of ceda, zeda the letter z, from Late Latin zeta — more at zed
First Known Use
1599, in the meaning defined above