Hal·lel /hɑˈle(ə)l/



 Hallel
      n : (Judaism) a chant of praise (Psalms 113 through 118) used at
          Passover and Shabuoth and Sukkoth and Hanukkah and Rosh
          Hodesh


 Hallel
    praise, the name given to the group of Psalms 113-118, which are
    preeminently psalms of praise. It is called "The Egyptian
    Hallel," because it was chanted in the temple whilst the
    Passover lambs were being slain. It was chanted also on other
    festival occasions, as at Pentecost, the feast of Tabernacles,
    and the feast of Dedication. The Levites, standing before the
    altar, chanted it verse by verse, the people responding by
    repeating the verses or by intoned hallelujahs. It was also
    chanted in private families at the feast of Passover. This was
    probably the hymn which our Saviour and his disciples sung at
    the conclusion of the Passover supper kept by them in the upper
    room at Jerusalem (Matt. 26:30; Mark 14:26).

      There is also another group called "The Great Hallel,"
    comprehending Psalms 118-136, which was recited on the first
    evening at the Passover supper and on occasions of great joy.