IPA: /ɪnˈvaɪtəˌtɔri/
KK: /ɪnˈvaɪtəˌtɔri/
Relating to or serving as an invitation.
The invitatory prayer is often used to welcome participants to the service.
A song or text used in church services to invite people to pray, often sung at the beginning of morning prayers.
The choir sang an invitatory to welcome the congregation to the service.
Invitatory is formed from "invitare" (meaning to invite) and the suffix "-ory" (meaning relating to or characterized by). The word refers to something that is related to or characterized by an invitation.
Think of 'inviting' someone — 'invitare' means to invite, and '-ory' indicates it relates to invitations.