Septuagesima comes from the Latin word for "seventieth." Likewise, Sexagesima, Quinquagesima, and Quadragesima mean "sixtieth," "fiftieth," and "fortieth" respectively. Septuagesima Sunday is so called because it falls within seventy days but more than sixty days before Easter. The next Sunday is within sixty, Sexagesima, and the next within fifty, Quinquagesima. Falling within forty days of Easter (excluding Sundays) the next Sunday is Quadragesima, the Latin word for the season of Lent, which (not counting Sundays) is forty days long. Because every Sunday recalls the resurrection of Christ, they are considered "little Easters" and not treated as days of penance.
The 17-day period beginning on Septuagesima Sunday is intended to be observed as a preparation for the season of Lent, which is itself a period of spiritual preparation for Easter. The “Alleluia” ceases to be said during the liturgy, and the Gloria in excelsis is not used. Likewise, violet vestments are worn, except on feasts, from Septuagesima Sunday until Holy Thursday.
O LORD, we beseech thee favourably to hear the prayers of thy people: that we, who are justly punished for our offences, may be mercifully delivered by thy goodness, for the glory of thy Name; through Jesus Christ thy Son our Lord, who liveth and reigneth with thee and the Holy Spirit, ever one God, world without end. Amen.