Sexagesima /sɛksəˈdʒɛsɨmə/, or, in full, Sexagesima Sunday, is the name for the second Sunday before Ash Wednesday in the Gregorian Rite liturgical calendar of the Roman Catholic Church, and also in that of some Protestant denominations, particularly those with Anglican and Lutheran origins.

The name "Sexagesima" is derived from the Latin sexagesimus, meaning "sixtieth," and appears to be a back-formation of Quinquagesima, the term formerly used to denote the last Sunday before Lent (the latter name alluding to the fact that there are fifty days between that Sunday and Easter, if one counts both days themselves in the total). Through the same process, the Sunday before Sexagesima Sunday was formerly known as Septuagesima Sunday, and marked the start of the Pre-Lenten Season which eventually became the time for carnival celebrations throughout Europe, this custom being later exported to places settled and/or colonized by Europeans. While Quinquagesima (50th day) is mathematically correct (allowing for the inclusive counting), Sexagesima and Septuagesima are only approximations (the exact number of days is 57 and 64 respectively). The earliest Sexagesima can occur is January 25 and the latest is February 28 (or February 29 in a leap year).