Passiontide (in the Christian liturgical year) is a name for the last two weeks of Lent, beginning on the Fifth Sunday of Lent, long celebrated as Passion Sunday, and continuing through Lazarus Saturday. It commemorates the suffering of Christ (Latin passio = “suffering”). The second week of Passiontide is Holy Week, ending on Holy Saturday.

"Passiontide" refers to the last two weeks of Lent. According to Cyril of Scythopolis, during this time the monks of the East, who had chosen the desert for a severer mode of life, returned to their monasteries.

In certain countries, such as Brazil and Italy, it is seen as the beginning of the Holy Week observances. The Viernes de Dolores (Friday of Sorrows) is a solemn pious remembrance of the sorrowful Blessed Virgin Mary on the Friday before Palm Sunday held in the fifth week of Lent.

In the Orthodox Church, the Fifth Saturday of Great Lent is known as the Saturday of the Akathist, when the "Akathist to the Theotokos" is sung at Compline.

In the Roman Catholic Church, Western Rite Orthodoxy, Lutheranism, and in Anglo-Catholic churches, all crucifixes and images may be covered in veils (usually violet, the color of vestments in Lent) starting on Passion Sunday: "The practice of covering crosses and images in the church may be observed, if the episcopal conference decides. The crosses are to be covered until the end of the celebration of the Lord's passion on Good Friday. Statues and images are to remain covered until the beginning of the Easter Vigil." (Specifically, those veils are removed during the singing of the Gloria.) The veiling was associated with Passion Sunday's Gospel (John 8:46–59), in which Jesus "hid himself" from the people.

In the Tridentine Mass, Psalm 42 (43) is omitted at all Masses (unless a feast is observed) until Holy Thursday inclusive, as is the short doxology (Gloria Patri) at the Introit and the Psalm Lavabo at Mass. It is likewise omitted in Psalm 94 at Matins, and the responds at Matins, Prime, Terce, Sext, None, and Compline. Also, the Preface for Lent gives way to the Preface of the Holy Cross unless a festal or votive Mass is celebrated for which a proper preface is assigned.

Passion Week is a name for the week beginning on Passion Sunday, as the Fifth Sunday of Lent was once called in the Roman Rite. In the 1955 Holy Week revisions, Passion Sunday was formally renamed from Dominica Passionis or Dominica de Passione ("Sunday of the Passion") to Dominica I Passionis, "First Sunday of the Passion" or "First Sunday of Passiontide". Palm Sunday, formerly Dominica in Palmis ("Sunday in Palms") became Dominica II Passionis seu in Palmis ("II Sunday of the Passion or in Palms").

Since the revision of the General Roman Calendar in 1969, the name "Passiontide" is no longer used for the last two weeks of Lent, although the former usage is somewhat preserved in the formal name for the Sunday before Easter, "Palm Sunday of the Lord's Passion". However, the Preface called that of the Passion of the Lord I (The Power of the Cross) is used in the fifth week of Lent and the Preface of the Passion of the Lord II (The Victory of the Passion) is used on Monday, Tuesday and Wednesday of Holy Week.