A cedilla ( sih-DIH-lə (from Spanish cedilla, "small ceda", i.e. small "z") or cedille (from French cédille, pronounced [sedij]) is a hook or tail ( ¸ ) added under certain letters as a diacritical mark to modify their pronunciation. In Catalan, French, and Portuguese (where it is called a cedilha) it is used only under the letter c (forming ç), and the entire letter is called, respectively, c trencada (i.e. "broken C"), c cédille, and c cedilhado (or c cedilha, colloquially). It is used to mark vowel nasalization in many languages of sub-Saharan Africa, including Vute from Cameroon.

This diacritic is not to be confused with the ogonek ( ̨ ), which resembles the cedilla but mirrored. It looks also very similar to the diacrital comma, mainly used for the Romanian script.