The following sites have Yiddish dictionaries:

Harkavy Yiddish Dictionary  Yiddish Dictionary online

A .  B .  C .  D .  E .  F .  G .  H .  I .   J .   K .   L .  M .  N .  O .  P .  Q .  R .  S .  T .  U .  V .  W .  X .  Y .  Z . 

Maamar, pl. Maamarim: lit. "word' or "written article'  A formal chassidic discourse delivered by a Rebbe.

Maariv: Also known as Arvit; the evening prayer established by Yaakov Avinu

Maaser: Tithing; to give a tenth of one’s earnings to the needy or charitable organizations

Machzor: A prayer book including only the prayers necessary for a specific Holiday with very involved prayer services, such as Rosh HaShanah and Yom Kippur

Maggid: preacher. Many of the first Rebbes were Maggidim (pl. of Maggid).

Maggid of Mezerich ("The Preacher of Mezerich"): Rabbi Dov Ber disiple of the Ba'al Shem Tov, and Rebbe of the Alter Rebbe.

MaHarsha: Hebrew initials for Moreinu HaRav Shmuel Eliezer (our teacher Rabbi Shmuel Eliezer) a famous Talmud commentator

Maimonides. (Rambam):See Rambam

Makkif: The transcendent dimension of the soul that is not consciously vested in the body.

Malach: An angel

Malachi: One of the books of the Tenach.

Malchus; lit. 'sovereignty'  The last of the ten Divine sefirot, and seventh of the emotive attributes in Creation.

Mashbak: An abbreviation of meshamesh bakodesh (one who serves in holiness). A personal secretary to the rebbe

Mashiach / Moshiach:"Anointed One," or "Messiah") A human being, the descendant of King David (Moshiach ben Dovid) who will gather the exiled Jewish People and bring them all back to Israel, rebuild the Holy Temple, inspire the whole world to believe in one G-d, and usher in an era of all human beings living together in peace and brotherhood.

Mashpia: A spiritual mentor for a Chabad chossid

Matzah; pl., Matzos:Unleavened bread eaten on Pesach.

Mazal Tov "A good sign": An expression of congratulations for the good fortune bestowed upon one from heaven.

Mazal ("sign," plural mazalot): A spiritual conduit of Divine beneficence; the 12 constellations of the zodiac.

Medayek: To make an inference or conclusion based on the precise wording.

Me'ein: a semblance of or a small portion. As in Shabbat is a semblance of the World to Come

Mefarshim: Rabbinic commentaries

Megilla: Tractate of the Talmud

MiKadsha v’Kaima: permanently sanctified. Shabbat is permanently sanctifies as opposed to Yom Tov which is sanctified via Beit Din

Melacha, Melachot: The 39 types of work related to the building of the Tabernacle, which are forbidden for Jews to take part in on the Sabbath.

Melachim: Kings

Melaveh Malkah "escorting the Queen": A meal or celebration held at the end of Shabbat (Shabbat being "the Queen").

Melech: King

Mem: The 13th letter of the Hebrew alphabet.

Menorah: The seven-branched candelabrum that was lit daily in the sanctuary of the Tabernacle and, afterwards, in the Holy Temple. Also referring to the eight-branched candelabrum used to kindle the Chanukah lights.

Mensch: Lit. “man,”  A person or connoting one who is a decent person.

Menachos: Tractate of the Talmud

Mercy (rachamim): The spiritual state associated with the sefirah of tiferet.

Mesiros Nefesh: self sacrifice

Mesorah: The transmitted traditions which comprise the basis of Jewish law; also, specific traditions regarding the exact text of the Written Torah.

Mesorah Torah law Kabbalah ("received tradition"): The body of classical Jewish mystical teachings

Metzitzah ("sucking"): The third phase of the rite of circumcision (milah). See milah, periah.

Mezuzah; pl., Mezuzos: Small parchment scroll written by a Sofer (scribe) and affixed to the doorpost, containing the first two paragraphs of Shema (Devarim (Deuteronomy) 6 -911 13-21).

Michah: Micah

Midah ("measure" or "attribute") pl. Midos: A character trait, either good or bad. 1. an attribute of God. 2. specifically, one of the sefirot from chesed to malchut, in contrast to the higher sefirot of the intellect. 3. one of the thirteen attributes of mercy, which are part of the revelation of keter.

Midda k'neged midda: measure for measure

Midrash pl. Midrashim: A major body of the oral Torah (after the Talmud), consisting of halachic or homiletic material and linguistic analyses of  Biblical text.

Mikveh "a gathering of water": Either a natural body of water or a specially-constructed pool used for ritual purification rites. See tumah and taharah.

Mil: a measure of distance, equivalent to approximately 1.087 kilometers.

Milah ("circumcision"): 1. the rite of circumcision, performed on a Jewish boy on the eighth day after his birth. 2. specifically, the first phase of this rite in which the foreskin is cut. See metzizah, periah.

Minhag: Custom

Minhag Rabboseinu Beyadeinu: Emulating the customs of our Rabbis

Minchah ("offering"): The afternoon prayer service, which was established by Yitchak (Isaac) Avinu. 2. A type of offering in Temple times

Minyan: A. quorum of at least ten adult males assembled for prayer or other mitzvah; b. place of public prayer; shul

Mishkan: The Tabernacle, i.e., the temporary Sanctuary in the wilderness; see Shmos (Exodubboseinu beyaddeinus) chapter 25ff.

Mishlei: Proverbs

Mishnah "Repetition": a six part review of Jewish law compiled in the 2nd century, which served as the focus of Talmudic interpretation; also a single passage of that work.

Mishnah Torah ("Repetition of the Torah "): The Rambam's systematization of the Oral Torah 2. Deuteronomy

Mispallel: To pray 

Mitzrayim: The land of Egypt

Mitzvah (pl., mitzvos): a religious obligation; one of the 613 Commandments 2. one of the seven commandments instituted by the sages.

Mitzvah Min HaMuvchar: The opportunity to perform a mitzvah in the most ideal fashion 

M'malai kol almin: the immanent Divine energy that vitalizes all elements within Creation and is thus accessible to conscious thought.

Mocha Stima'ah ("the hidden brain" Aramaic):The chochmah of Arich Anpin. In psychological terms, the power to generate new insight.

Mochin d'Ima ("brains of Imma" Aramaic): A state of consciousness or mentality, or cognitive life-force in which one experiences binah, or understanding or rationality.

Modeh Ani ("I Acknowledge"): The thanksgiving prayer recited upon awakening each morning.

Molad:  ("time of birth") The time when the moon begins its monthly cycle.

Mori: my teacher/master.

Moshe Rabbeinu: Moses our teacher. A common Jewish way of referring to Moses.

Motzaei Shabbos/Motzaei Yom Tov: evening on which a Shabbos or Yom-Tov ends

Mum: A blemish, particularly in regard to priests and animals designated for ritual sacrifice.

Musaf: the additional prayer service recited on Shabbat, Rosh Chodesh, Rosh HaShanah, Yom Kippur and Yom Tov.

Mussar (“rebuke”): a movement of Judaism that encourages people to study ethics and morals and to improve character.