That which invites; specifically, the invitatory psalm, or a part of it used in worship.

At Morning Prayer: the Venite, Psalm 95, Jubilate, or Christ our Passover; at Evening Prayer: 0 Gracious Light (Phos Hilaron) or other suitable hymn or psalm. The invitatory is used at the beginning of an Office after the opening versicle and response and before the appointed psalms.

The Invitatory is a psalm, traditionally numbered 94 in the Septuagint or 95 in the Masoretic text , used to start Matins in the Divine Office. After the reform of the Liturgy of the Hours after the Second Vatican Council, the Invitatory is said either before the Office of Readings or Lauds, whichever is said first in a day; also several other psalms may be substituted.

conveying an invitation; "a brief invitatory note"

Using or containing invitations.