Antisemitism: hostility toward or hatred of Jews as a religious or ethnic group, often accompanied by social, economic, or political discrimination.

Appellplatz: German word for roll call square where prisoners were forced to assemble.

Aryan: Term used in Nazi Germany to refer to non-Jewish and non-Roma (Gypsy) Caucasians. Northern Europeans with especially "Nordic" features such as blonde hair and blue eyes were considered by so-called race scientists to be the most superior of Aryans, members of a "master race."

Auschwitz: the largest Nazi concentration camp complex, located 37 miles west of Krakow, Poland. The Auschwitz main camp (Auschwitz I) was established in 1940. In 1942, a killing center was established at Auschwitz-Birkenau (Auschwitz II). In 1941, Auschwitz-Monowitz (Auschwitz III) was established as a forced-labor camp. More than 100 subcamps and labor detachments were administratively connected to Auschwitz III.

Birkenau: Nazi camp also known as Auschwitz II (see Auschwitz above), Birkenau contained systematic mass killing operations. It also housed thousands of concentration camp prisoners deployed at forced labor.

Buchenwald: a large concentration camp established in 1937 by the Nazis. It was located in north-central Germany, near the city of Weimar.

Buna: Industrial plant established by the I.G. Farben company on the site of Auschwitz III (Monowitz) in German-occupied Poland. I.G. Farben executives aimed to produce synthetic rubber and synthetic fuel (gasoline), using forced labor. Thousands of prisoners died there.

Concentration camp: Throughout German-occupied Europe, the Nazis established camps to detain and, if necessary, kill so-called enemies of the state, including Jews, Gypsies, political and religious opponents, members of national resistance movements, homosexuals, and others. Imprisonment in a concentration camp was of unlimited duration, was not linked to a specific act, and was not subject to any judicial review. In addition to concentration camps, the Nazi regime ran several other kinds of camps including labor camps, transit camps, prisoner-of-war camps, and killing centers.

Crematorium: a facility containing a furnace for reducing dead bodies to ashes by burning.

Criminal Police (Kripo): German police detective force responsible for investigating non-political crimes.

Einsatzgruppen: mobile units of the German Security Police and SD augmented by Order Police and Waffen-SS personnel.

These units followed the German army as it invaded the nations of central and eastern Europe. Their duties included the arrest or murder of political opponents and potential resistance. In Poland in 1939, these units were assigned to shoot Polish intellectuals and to concentrate the Jewish population into large cities. After the German invasion of the Soviet Union in 1941, Einsatzgruppen personnel killed Jews, Soviet political commissars, Gypsies (Roma), mentally disabled persons, and other perceived "racial" and ideological enemies, usually by mass shootings.

Euthanasia: "euthanasia" (literally, "good death") usually refers to the inducement of a painless death for a chronically or terminally ill individual. In Nazi usage, however, "euthanasia" was a euphemistic term for a clandestine program which targeted for systematic killing institutionalized mentally and physically disabled patients, without the consent of themselves or their families.

Fascism: a political movement that exalts the collective nation, and often race, above the individual and that advocates: a centralized totalitarian state headed by a charismatic leader; expansion of the nation, preferably by military force; forcible suppression and sometimes physical annihilation of opponents both real and perceived.

“Final Solution”: the Nazi plan to annihilate the European Jews.

Generalgouvernement (General Government): that part of German-occupied Poland not directly annexed to Germany, attached to German East Prussia, or incorporated into the German-occupied Soviet Union.

Gestapo: the German Secret State Police, which was under SS control. It was responsible for investigating political crimes and opposition activities.

Ghetto: a confined area of a city in which members of a minority group are compelled to live.

The first use of the term “ghetto” for a section of a city in which Jews lived was in Venice, Italy, in 1516.

Gypsy: a traditional term, sometimes perceived as pejorative, for Roma, a nomadic people whose ancestors migrated to Europe from India. Nazi Germany and its Axis partners persecuted and killed large numbers of Roma during the era of the Holocaust.

Heydrich, Reinhard: (1904–1942) SS General and chief of the Security Police and SD. Sometime in December 1940, Heydrich was tasked with developing a "Final Solution" of the Jewish question in Europe.

Himmler, Heinrich: (1900–1945) Reichsführer-SS (Reich Leader of the SS) and Chief of German Police, a position which included supreme command over the Gestapo, the concentration camps, and the Waffen-SS. After 1943, Himmler was Minister of the Interior of Nazi Germany, principal planner for the aim of Nazi Germany to kill all European Jews.

Hitler, Adolf: (1889–1945) Führer (leader) of the National Socialist (Nazi) movement (1921–1945); Reich Chancellor of Germany 1933–1945; Führer of the German Nation (1934–1945).

Holocaust: The Holocaust was the state-sponsored systematic persecution and annihilation of European Jewry by Nazi Germany and its collaborators between 1933 and 1945. Jews were the primary victims. Six million were murdered.

Kapo: a concentration camp prisoner selected to oversee other prisoners on labor details. The term is often used generically for any concentration camp prisoner to whom the SS gave authority over other prisoners.

Killing centers: The Nazis established killing centers for efficient mass murder. Unlike concentration camps, which served primarily as detention and labor centers, killing centers (also referred to as "extermination camps" or "death camps") were almost exclusively "death factories." German SS and police murdered nearly 2,700,000 Jews in the killing centers either by asphyxiation with poison gas or by shooting.

Kommando: German word for detachment, such as a detachment of concentration camp prisoners at forced labor.

Kristallnacht: usually referred to as the "Night of Broken Glass." It is the name given to the violent anti-Jewish pogrom of November 9 and 10, 1938. Instigated primarily by Nazi party officials and the SA (Nazi Storm Troopers), the pogrom occurred throughout Germany, annexed Austria, and the Sudetenland region of Czechoslovakia.

Mengele, Josef: (1911–1979) SS physician assigned to Auschwitz; notorious for conducting so-called medical experiments on inmates, especially twins and dwarfs.

Ordnungspolizei (Order Police; Orpo): regular uniformed German police force. Central Headquarters were in Berlin. Municipal Police (Schutzpolizei) served as the urban police forces. Gendarmerie, or rural police, served in the countryside. There were also larger units of Order Police called Police Battalions.

Preventive Arrest (Vorbeugungshaft): Instrument of detention that permitted criminal police detectives to take persons suspected of engaging in criminal activities into custody without warrant or judicial review of any kind. Preventive arrest usually meant indefinite internment in a concentration camp.

Protective Detention (Schutzhaft): Instrument of detention that permitted secret state police detectives to take persons suspected of pursuing activities hostile to state interests into custody without warrant or judicial review of any kind. Protective custody most often meant indefinite internment in a concentration camp.

Red Army: the army of the Soviet Union.

Reich Security Main Office (Reichssicherheitshauptamt; RSHA): Headquarters of the Commander of the Security Police and SD. Included the central offices of the Gestapo, the Kripo, and the SD. Commanded by Reinhard Heydrich and, later, Ernst Kaltenbrunner.

"Resettlement": a Nazi euphemism for deportation and murder.

Reich Commissariat Ostland: a German civilian occupation region that included the Baltic States and most of Belarus.

SS: German abbreviation for Schutzstaffel (literally, protection squads). A paramilitary formation of the Nazi party initially created to serve as bodyguards to Hitler and other Nazi leaders. It later took charge of political intelligence gathering, the German police and the central security apparatus, the concentration camps, and the systematic mass murder of Jews and other victims.

Sachsenhausen: the principal Nazi concentration camp for the Berlin area.

Security Service (Sicherheitsdienst; SD): an SS agency which served as the political intelligence service of the Nazi party and, later, of the German Reich. The SD also claimed to be the repository of the intellectual elite of the Nazi SS. The SD played a central role in carrying out the Holocaust. All key departments of the Security Police were commanded by SD officers.

Sonderkommandos (special detachments): in killing centers, Sonderkommandos consisted of those prisoners selected to remain alive as forced laborers to facilitate the killing process, particularly the disposal of corpses.

Synagogue: in Judaism, a house of worship and learning.

Upper Silesia: an area that Nazi Germany annexed in 1939 after invading and conquering Poland.

Weimar Republic: Name for the parliamentary democracy established in Germany from 1919–1933, following the collapse of Imperial Germany and preceding Nazi rule.

Yellow star: a badge featuring the Star of David (a symbol of Judaism) used by the Nazi regime during the Holocaust as a method of visibly identifying Jews.