mussaf means an additional prayer service recited on holy days (Shabbat, Yom Tov, Chol HaMoed, and Rosh Chodesh). Lexicurio rates it Sui generis — a strength score of 87 out of 100.
Etymology
From Hebrew מוסף (musáf).
noun
- An additional prayer service recited on holy days (Shabbat, Yom Tov, Chol HaMoed, and Rosh Chodesh).“Exemplary in this regard is the thematic centrality of Obad. 1:21 in Jewish liturgy, because it serves as one of the climactic verses in part of the Rosh ha-Shanah Musaf service (known as Malkhuyot), celebrating and proclaiming God's future kingdom or dominion.”