machzor
"Cycle;" High Holiday prayerbook; plural: machzorim.
Shabbat Shuvah
"Sabbath of Return;" the Shabbat (sabbath) between the holidays of Rosh HaShanah and Yom Kippur. A special haftarah is read and traditionally the rabbi gives a sermon related to repentance.
shofar
Ram’s horn most commonly blown throughout the month of Elul and during the High Holiday season.
Selichot
"Forgiveness;" special penitential prayers recited during Elul and the High Holidays.
Tashlich
"Casting away;" A traditional ceremony held during the Yamim Nora-im (Days of Awe), usually on the first day of Rosh HaShanah, in which individuals symbolically “cast away” their sins or wrongdoings from the past year by throwing breadcrumbs into a flowing body of water.
T'shuvah
Tishrei
Seventh month on the Hebrew calendar; Rosh HaShanah falls on the first day of this month.
Tu BiShvat
"15th of Shevat;" New Year of the Trees; Jewish Arbor Day, which is a minor festival.
Yom HaDin
"Day of Judgement;" alternate name for Rosh HaShanah
Yom Tov
"Good Day;" the term, often pronounced as yuntiff (Yiddish) has come to mean "holiday;" "Good Yuntiff" is often used a holiday greeting.