Mokum is the Yiddish

Yiddish language

Yiddish is a High German language of Ashkenazi Jewish origin, spoken throughout the world. It developed as a fusion of German dialects with Hebrew, Aramaic, Slavic languages and traces of Romance languages...

 word for "place" or "safe haven". It is similar to the Hebrew

Hebrew language

Hebrew is a Semitic language of the Afroasiatic language family. Culturally, is it considered by Jews and other religious groups as the language of the Jewish people, though other Jewish languages had originated among diaspora Jews, and the Hebrew language is also used by non-Jewish groups, such...

 word makom (מקום, "place"), from which it is derived. In Yiddish the names of some cities in the Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 and Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 were shortened to Mokum and had the first letter of the name of the city, transliterated into the Hebrew alphabet

Hebrew alphabet

The Hebrew alphabet , known variously by scholars as the Jewish script, square script, block script, or more historically, the Assyrian script, is used in the writing of the Hebrew language, as well as other Jewish languages, most notably Yiddish, Ladino, and Judeo-Arabic. There have been two...

, added to them. Cities named this way were Amsterdam

Amsterdam

Amsterdam is the largest city and the capital of the Netherlands. The current position of Amsterdam as capital city of the Kingdom of the Netherlands is governed by the constitution of August 24, 1815 and its successors. Amsterdam has a population of 783,364 within city limits, an urban population...

, Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

, Delft

Delft

Delft is a city and municipality in the province of South Holland , the Netherlands. It is located between Rotterdam and The Hague....

, and Rotterdam

Rotterdam

Rotterdam is the second-largest city in the Netherlands and one of the largest ports in the world. Starting as a dam on the Rotte river, Rotterdam has grown into a major international commercial centre...

.

Mokum, without Aleph

Aleph

* Aleph or Alef is the first letter of the Semitic abjads descended from Proto-Canaanite, Arabic alphabet, Phoenician alphabet, Hebrew alphabet, Syriac alphabet-People:*Aleph , an Italo disco artist and alias of Dave Rodgers...

, is still used as a nickname

Nickname

A nickname is "a usually familiar or humorous but sometimes pointed or cruel name given to a person or place, as a supposedly appropriate replacement for or addition to the proper name.", or a name similar in origin and pronunciation from the original name....

 for Amsterdam. The nickname was first considered to be Bargoens

Bargoens

Bargoens is a form of Dutch slang. More specifically, it is a cant language that arose in the 17th century, and was used by criminals, tramps and travelling salesmen as a secret code, like Spain's Germanía or French Argot....

, a form of Dutch slang, but in the 20th century it lost its negative sound and is now used as a nickname for Amsterdam in a sentimental context.