wikipedia | A tabernacle is the fixed, locked box in which, in some Christian churches, the Eucharist is "reserved" (stored). A less obvious container, set into the wall, is called an aumbry.
Within Catholicism, Eastern Orthodoxy and in some congregations of Anglicanism and Lutheranism, a tabernacle is a box-like vessel for the exclusive reservation of the consecrated Eucharist.
It is normally made of metal, stone or wood, is lockable and secured to
its altar to prevent the consecrated elements within from being removed
without authorization. The "reserved Eucharist" is secured there for
distribution at services, for availability to bring Holy Communion
to the sick, and, especially in the Western Church, as the center of
attention for meditation and prayer. The term "tabernacle" arose for
this item as a reference to the Old Testament tabernacle which was the
locus of God's presence among the Jewish people - hence, it was formerly
required (and is still generally customary) that the tabernacle be
covered with a tent-like veil or curtains across its door when the
Eucharist is present within.
By way of metaphor, Catholics and Orthodox alike also refer to the Blessed Virgin Mary as the Tabernacle in their devotions (such as the Akathist Hymn or Catholic Litanies to Mary), as she carried within her the body of Christ in her role as Theotokos.
