Laetare and Gaudete are from the Latin language. Gaudete (from the Latin for “rejoice”) is celebrated on the Third Sunday of Advent.
It is a special day because the preparation for the Solemnity of Christmas is half over. On this day, the vestments, altar cloth, and tabernacle veil are rose-colored instead of the penitential purple. The word Gaudete can be found in Philippians 4:4–5, “Rejoice in the Lord always; again I will say, Rejoice. Let all men know your forbearance. The Lord is at hand.” This forms the Entrance Antiphon of the Mass.
Laetare Sunday is celebrated on the Fourth Sunday of Lent.
It signals that Lent is half over and the Solemnity of Easter will soon arrive, encouraging believers not to lose heart or give up their Lenten commitments. Rose-colored vestments, altar cloths, and tabernacle veil may be employed and flowers can adorn the altar. During Lent, flowers are forbidden in the Sanctuary until Easter except for Laetare Sunday.
The second reading for the Fourth Sunday of Lent cycle “C” which is from Philippians 4:4–7 is the basis for Laetare, which reads “Laetare Domine semper” (Rejoice in the Lord always): “Have no anxiety about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God which passes all understanding will keep your hearts and your minds in Christ Jesus.”