Mass (liturgy)
The term comes from the late-Latin word missa (dismissal), a word used in the concluding formula of Mass in Latin: "Ite, missa est" ("Go, it is the dismissal"). Dismissal means that someone is allowed to leave. In this case, people are being allowed to leave because Mass is finished. In another sense, it also means that people are allowed to leave to go on a mission to tell other people about Jesus and Christianity.