+ Aliyah - A section of the day's Torah reading.  One person is
called for each section.

Amen - "Agreed," from the same root as Emunah, belief, and
Ne'eman, trustworthy.

Baal_Tosif - "You should not add on," referring to a commandment
in the Torah not to add to the commandments.

B'dieved - means "after the fact" - having already done
something which conflicts with the ideal, has one at least done
enough to fulfill his obligations.  See also L'chatchila.

Chol HaMoed - lit. the Intermediate Days; the "work days" of 
Passover and Sukkos. The Festivals of Passover and Sukkos both 
have holidays at the beginning and end (though technically the 
holiday at the end of Sukkos is a separate holiday), and 
"intermediate days" in the middle.  During these days, much 
work is permitted, but many holiday laws remain in effect.

HaShem - lit. the name.  Commonly used to refer to G-d, while
avoiding casual use of His name in conversation.

Kaddish - An Aramaic declaration of the holiness of G-d's name,
said several times during services when praying with a minyan 
(10 Jewish men).

Karmelis - A semi-private domain.  While the Torah prohibits
carrying on the Sabbath in the public domain, an enactment by
the Sages extended this prohibition to a Karmelis as well, in
order that people not become confused.

K'dei Dibur - lit. enough (time) to talk, referring to the time
needed to say "Shalom Aleichem Rebbe U'Mori," i.e. several
seconds.

Kedushah - Declaration of the holiness of G-d's name, said during 
the chazzan's repetition of the Amidah, the standing prayer.

Kelayim - refers to mixtures of species prohibited by Torah Law,
such as wool and linen.

L'chatchila - means "before the fact" - before doing something,
one wants to know the ideal and best way to go about it.  See
also B'dieved.

Lulav - One of the "four species" taken on Sukkos, but often used
colloquially to refer to all four. During the Sukkos holiday, there is a
Mitzvah to take four species - the Lulav, a palm frond; the Esrog, a species
of citrus fruit; the Hadas, myrtle; and Aravah, willow - and wave them in a
special ceremony.

Onen - One who has an unburied close relative. This person is
exempt from the performance of positive commandments until the
funeral takes place (except on the Sabbath or holidays).

Rosh Chodesh - "The Head of the Month."  This semi-holiday
occurs for one or two days of each month - on the first day of
every month, and also on the thirtieth day of a Jewish month, if
any (Jewish months are 29 or 30 days, so in the latter case Rosh
Chodesh is on the thirtieth of one month and the first day of
the next).

Schach - The covering of a Sukkah. This covering must consist of natural
growth that does not provide a complete cover - such as bamboo or tree branches.

Shemoneh Esrei - Lit. 18.  Refers to the main "Amidah," the
prayer said while standing that is the central part of every
prayer service. Though the weekday version of this prayer now
contains nineteen blessings, one of these is a later addition to
the original formulation. Thus this prayer is often referred to
in Rabbinic sources simply as "the 18."

Shofar - A ram's horn, blown during the Rosh Hashanah services.

Sukkah - The special booths used during the holiday of Sukkos. During this
seven-day holiday, there is a commandment to live in these booths, meaning
primarily to eat and sleep there (one is exempt during rainfall or extreme
cold).

Ta'aseh v'lo min ha'asui - "Making, and not that which is
already made." This principle can be described as the "pre-fab"
law.  One cannot make Tzitzis and then place them on a garment,
or put Tzitzis on a garment and then make the garment
four-cornered.  Similarly, one cannot put the covering on a
Sukkah and only then ensure that the Sukkah has the requisite
three walls.  First the object must be Kosher to receive the
Mitzvah addition, and then the Mitzvah object - Tzitzis or
Schach - may be added.

Tallis Katan - lit. small garment.  Refers to a small
four-cornered garment, with Tzitzis attached, customarily worn
throughout the day.

Tcheles - Blue-Green, a color required for threads of Tzitzis by
the Torah.  Today we do not know how to make this color, so the
Biblical requirement remains to make Tzitzis, but all eight
threads of our Tzitzis are white.

Tefillin - Phylacteries, worn by men during morning prayers.

Tefillin Shel Rosh - lit. Tefillin of the head - Of the two 
Tefillin, the one worn on the head.

Tefillin Shel Yad - lit. Tefillin of the hand - Of the two 
Tefillin, the one worn on the arm.

Tzitzis - Fringes, cf. Numbers 15:38, "...they shall make
fringes for themselves on the corners of their garments."

Yahrtzeit - The anniversary of a death.

' Ari - or Ari Zal, Rabbi Yitzchak Luria, often considered the
father of present-day Kabbalah. The acronym stands for "our
father, Rabbi Yitzchak (Zal - of blessed memory)".

Bach - Bayit Chadash, Commentary on the Tur.

Bais Yosef - Commentary on the Tur by Rabbi Yosef Karo, author
of the Shulchan Aruch. Written before the Shulchan Aruch, it
often provides insights and the reasons for Rabbi Karo's final
decision as stated in the Code.

Biur Halacha - Additional Halachic discussion, written as a
companion text by the author of the Mishna Brurah.

Darchei Moshe - Commentary on the Tur written by Rabbi Moshe
Isserles, the Rema, whose comments are interwoven into the
Shulchan Aruch.

Chayei Adam - Halachic Compendium, 19th C. C.E.

Elya Raba - Halachic Compendium, 19th C. CE.

Gra - Transliterated acronym for the Gaon Rabbi Eliyahu,
referring to Rabbi Eliyah Kramer of Vilna.  He is universally
considered to be without peer amongst the later authorities, in
terms of both the breadth and depth of his Torah knowledge.  His
commentary to the Shulchan Aruch is printed on each page of the
latter text in standard editions.

Levush - Halachic Compendium, 16th C. C.E.

Magen Avraham - Commentary on Shulchan Aruch.

Olas Tamid - Halachic compendium.

Prishah - Commentary on the Tur.

Pri Megadim - Commentary on both the Magen Avraham and Taz 
commentaries (on the Shulchan Aruch).

Rema - Rabbi Moshe Isserles, who was going to write his own
Halachic compendium but stopped when he learned that Rabbi Yosef
Karo was in the process.  Instead, Rabbi Isserles wrote glosses
to the Shulchan Aruch that tend to outline where his own
Ashkenazic practice differed from that of the Sephardic Rabbi
Karo.

Rosh - Early authority - one of the group of Rabbis that produced 
the "Tosfos" commentary on Talmud in the 13th Century CE. Also
wrote Halachic rulings as part of his own Talmudic commentary.  
Father of the Tur.

Shaarei Teshuva - Commentary on Shulchan Aruch by Rabbi Chaim M.
Margolius.

Shulchan Aruch - the Code of Jewish Law, by Rabbi Yosef Karo -
also author of the Bais Yosef commentary on the Tur.

Taz - Acronym for Turei Zahav, commentary on the Shulchan Aruch.

Tur - Halachic compendium immediately predating the Shulchan
Aruch. It is one of the three primary sources for Halachic
rulings in the Shulchan Aruch (the others being the Mishnah Torah
of the Rambam, and the decisions of the Rosh), and provides the 
basic structure (the four major sections and the order of 
Simanim).