The following sites have Yiddish dictionaries:

Harkavy Yiddish Dictionary  Yiddish Dictionary online

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Sabbath: See Shabbat.

Safra d'Tzniuta ("The Book of Modesty"): A a section of the Zohar.

Sages (in Hebrew, "Chazal" or "Razal"):  The "Sages" are the Rabbis of the Talmudic period. Their wordsrecorded in the Talmud, the Midrash and the Zoharconstitute the "OralTorah."

Samech: The 15th letter of the Hebrew alphabet.

Sanhedrin: Tractate in the Talmud. Body of 72 Supreme court justices

Sason ("joy"): See Chedvah.

Seah: A unit of measure, equivalent to approximately 6 liters.

Second Holy Temple: Stood for 420 years in Jerusalem until destroyed by the Romans in 68 c.e. The First Holy Temple was built by King Solomon and was destroyed 410 years later by the Babylonians in 423 bce. The Third Holy Temple will be built by the Messiah and never again destroyed.

Seder pl., Sedarim:  Lit "Order".  1. The service observed on the first night(s) of Pesach. 2. The order or program of things e.g. Avodah, verses etc.

Sefer (seforim): A Jewish religious book.

Sefer Torah, pl. Sifrei Torah: Torah scroll.

Sefer Yetzirah: ("The Book of Formation"). Sefer Yetzirah, the very first classic text of Kabbalah, is attributed to Abraham. It was afterwards edited by Rabbi Akiva.

Sefer HaChinuch: ("The Book of Education"). Sefer Hachinuch is a popular medieval work that enumerates the 613 commandments of the Torah (based upon Maimonides' system of counting) and explains them both from a legal and a moral perspective.

Sefirah (pl., Sefiros): divine attributes or emanations which are manifested in each of the Four Worlds, and are the source of the ten corresponding faculties (kochos) of the soul

Sefirat HaOmer ("counting the Omer"): The omer is a dry measure mentioned in the Torah, and refers specifically to the measure of barley offered in the Temple on the second day of Pesach. Beginning with this day, the Jew is commanded to count the next forty-nine days, after which, on the fiftieth day, falls the holiday of Shavuot.

Segal: Hebrew for 'Segan L'Kohen' assistant to the priest. refers to one who is of the tribe of Levi.

Seichel: analytical intelligence, intellect or thought

Seichel haNe’elam mikol ra’ayon: A level of (G-dly) intellect that is hidden from all conception

Segulah: A deed, object, or utterance that acts as a charm or protection that effects spiritual or material benefits.

Self-nullification or Selflessness (Bitul):"Self-nullification" is the spiritual state associated with the inner experience of chochmah.

Semichah ("support"): 1. The act of pressing down on the head of an animal prior to offering it as a sacrifice; 2.Rabbinic ordination.

Sephardi(m): Jews of Southern European, North African, and Middle Eastern descent. Ashkenazi Jews come from the rest of Europe and Russia.

Serafim ("fiery angels"): Six-winged angels seen by Isaiah in his first prophetic vision of the heavenly throne; the angels occupying the world of Beriah.

Seudas Moshiach:The Festive Meal of Moshiach held on the Last Day of Pesach.

Seventeenth of Tammuz, the Fast of: Fast commemorating 5 calamities, including the breaching of the walls of Jerusalem during the Roman siege.

Sever panim yafot: a pleasant countenance. Avot (1:15) states:"Greet every person with a pleasant countenance"

Sha'ashuim Atzmi'im ("The Delights of Self"): The first level of the revelation of God's inner light. Also called Sha'ashuei Hamelech b'Atzmuto ("The Delights of the King in Himself").

Shabbat/Shabbos ("Sabbath"): Shabbat is the holy day of rest beginning sunset on Friday and ending at nightfall on Saturday, every week.

Shabbaton:A Shabbat gathering

Shabbos Chazon: Shabbos before Tisha B'Av

Shabbos Nachmu: Shabbos after Tisha B'Av

Shabbos Parshas..:The Shabbos on which a named parshah is read.

Shabbos Tshuva: Shabbos between Rosh HaShanah and Yom Kippur

Shabbos: Tractate in the Talmud

Shacharit/Shacharis: morning prayer service

Shaidim: demons

Shakai: A Holy Name of God.

Shaliach (pl. Shluchim): An emissary of the Rebbe, sent to spread Yiddishkeit and Chassidus

Shalom Bayis:  Lit "peace in the home" Peaceful relations between husband and wife

Shavuos:  lit.'weeks'  1.Festival commemorating the Giving of the Torah at Sinai  2. Tractate in the Talmud.

Shechitah: Ritual slaughtering.

Shechinah: The immanent Divine Presence that inheres within the universe, corresponding to the sefirah of malchut, the "feminine" aspect of Divinity.

Shehecheyanu:  lit. 'Who has granted us life':Blessing pronounced on seasonal and other occasions for thanksgiving (Siddur Tehilat HaShem, p. 87).

Shekel ("weight"): A weight measure of silver, equivalent to approximately 12.3 gram.

Shema Yisrael 

Shema Yisrael "Hear O' Israel": Prayer proclaiming the Oneness of G-d, the cornerstone of Jewish faith, that is recited twice a day, once in the evening and once in the mording. It is a compilation of three Biblical passages Deut 6 4-9, 11 13-21, Numbers 15 37-41.

Shneur Zalman of Liadi, Rabbi Rabbi Shneur Zalman of Liadi, known as the Alter Rebbe ("the old Rabbi") (Elul 18 5505 "1745" - Tevet 24 5573 "1813". Also known as The Rav and as Ba'al HaTanya. He was the founder of the Chabad-Lubavitch philosophy and trend within the Chassidic movement. 

Shofar: Ram's horn sounded on Rosh HaShanah.

Shtender: A stand or lectern, where books were placed during learning, or where a prayer book was placed by prayers.

Shulchan Aruch "Set Table":The Code of Jewish Law, compiled and redacted by Rabbi Yosef Karo 1488-1575.

Shulchan Aruch HaRav (Admor HaZaken): Code of Jewish Law compiled by Rabbi Shneur Zalman

Sicha (pl. Sichos):A public address of the Rebbe or one of the earlier Rebbe’im

Siddur, pl. Siddurim, lit.,: order of prayers':Prayer book; page references in most articles on this site are to the edition (with English translation) entitled Siddur Tehillat HaShem (Kehot, N.Y., 1979).

Sifrei: Midrashic work on Devorim

Siman, pl. simanim: 1. significant omens 2. signs depicting an object 3. Chapters in the the Shulchan Aruch or other books

Se'if : Specific halachot or articles within a chapter 

Simchah:("Joy" or "happiness").

Simchas Torah:  lit. The Rejoicing of the Torah':Festival immediately following Sukkos, on which the public reading of the Torah is annually concluded and recommenced; in Eretz Yisrael coincides with Shemini Atzeres, and in the Diaspora falls on the following day.

Sincerity (temimut):"Sincereity" is the spiritual state associated with the sefirah of hod.

Sivan: The third of the twelve months of the Jewish calendar.

Siyyum: lit.: conclusion':Celebration marking one's completion of a Talmudic tractate.

Slichos: Penitential prayers said on the days before Rosh HaShanah and Yom KIppur

Sod: The level of Torah interpretation that plumbs its Kabbalistic or mystical depths. sod A method of Biblical interpretation based on describing secret

Sodom: Biblical city filled with wicked people

Sota: A wife suspected of adultery. Tractate of the Talmud

Soul:1. The Neshama The ?breath of life? that G-d breathed into the first man; the third of the five levels of soul, associated with the vitality of intelligence. 2.The third of the five levels of the soul. 3. The soul in general. See soul.

Sovev Kol Almin ("Encompassing all Worlds"): the transcendent Divine energy that permeates the universe but eludes our conscious grasp.

Splendor (Hod): the eighth of the ten sefirot, and fifth of the emotive attributes in Creation.

Strakes: Strips of velvet sown into the garments of some of the Rebbes, or great Rabbis.

Sukkah ("Hut"): 1, A temporary dwelling occupied during the festival of Sukkot in symbolic demonstration of our faith in God's providence. 2.Tractate in the Talmud

Sukkot ("Hu ts"): the 7-day festival celebrating the gathering of the harvest and commemorating the Divine protection afforded the children of Israel as they trekked through the desert after the Exodus from Egypt.