In my experience, "Mizpah" is used in the phrase, "Mizpah
benediction." It comes from Genesis 31:49, in which Jacob and his
father-in-law, Laban, make a treaty with each other.
The Hebrew root is sade-pey-hey, meaning "to look out, spy, keep
watch." Mizpah is the nominal form, meaning approximately, "Outlook
point," or "watch-tower."
The part of the verse used as a "benediction" is (in the King James
Version), "May the Lord watch between me and thee, when we are
absent, one from the other." It sounds good as a benediction, but the
modern irony is that in its ancient context, the passage is closer to
being a threat, since Jacob has finally left Laban (whose daughters
are Jacob's wives, and whose flocks Jacob has earned and taken) and
is headed back to Palestine. Laban pursues them, but eventually
realizes he cannot prevail. So he makes a treaty (covenant) with
Jacob, using a pile of rocks as witness of the treaty, that Jacob
always treat his wives fairly and that Jacob and Laban stay out of
each other's territory. Laban calls the place "Galeed" and also
The benediction understanding is the way that "Mizpah" is most often
used in the Church; how the word may be used in the synagogue or
elsewhere is beyond my experience.