I found this article on Good Spark Garage and, from their links, it appears to have all been researched via Wikipedia. Some you’ll know. Other’s? Perhaps not. I’ve made a few changes from the original article, adding some detail and photo’s in places.
AJS: Albert John Stevens
The origin can be traced back to the early 1900′s when the Stevens brothers – Harry, George, Jack and Joe set about producing AJS motorcycles.The initials AJS were taken from Albert John (Jack) Stevens, the only brother to have a middle name.
|The Stevens brothers (standing) with 4 riders before the 1914 TT
ATK: Anti-Tension Kettenantrieb
The name “ATK” comes from a device patented in the 1980s by ATK’s founder, Austrian-born engineer Horst Leitner, that eliminates chain torque for improved handling (translation of kettenantrieb is “chain drive”).
BETA: Enzo Bianchi and Arrigo Tosi,
Beta originated in 1904 as a bicycle manufacturing company. It began making motorcycles in 1948. The name Beta comes from the initials of the men who ran the company at that time.
Bimota: Bianchi Morri Tamburini.
Bimota is a small, Italian motorcycle manufacturer founded in 1973 by Bianchi, Morri and Tamburini. Bimota concentrated initially on building high-quality motorcycles around existing engines.
BMW: Bayerische Motoren Werke
(English:Bavarian Motor Works) BMW originated following a restructuring of the Rapp Motorenwerke aircraft engine manufacturing firm in 1917. They began building complete motorcycles after WWI.
BSA: Birmingham Small Arms
BSA was a group of business that manufactured military and sporting firearms, bicycles, motorcycles, cars, buses, and many other metal-related products. It began in 1861 by 14 gunsmiths.
Bultaco: Francisco “Paco” Bultó
The Bultaco motorcycle company started in 1958 by Francisco Bultó, a former director of Montessa. The name comes from combining the first four letters of Sr. Bultó’s surname with the last three of his nickname “Paco.”
|Bultaco Pursang 370
Cagiva: Castiglioni Giovanni Varese
Thename is derived from the founder and the founding location. Cagiva was a manufacturer of small metal components founded in 1950 by Giovanni Castiglioni in Varese, Italy. It went into the motorcycle industry in 1978.
CCM: Clews Competition Motorcycles
A British motorcycle manufacturer based in England. CCM was born out of the collapse of BSA’s Competition Department in 1971. Alan Clews, founder, was a successful Trials and Scrambles rider in the late 1960s.
CZ: Ceská Zbrojovka
CZ is a Czech firearms manufacturer also known for making CZ motorcycles. It was established as a branch of the Skoda Works Armament in Czechoslovakia in 1919.
DERBI: Derivados de Bicicletas
The name Derbi acknowleges of the company’s history and is an acronym for DERivados de BIcicletas (derivatives of bicycles) It began as a bicycle workshop near Barcelona in 1922.
DKW: Dampf Kraft Wagen
After creating a dampf kraft wagen (steam-driven car) in 1916, Jørgen Skafte Rasmussen created a motorcycle called Das Kleine Wunder (the little marvel). By the 30s, Germany-based DKW was the largest motorcycle manufacturer.
|Replica 1930′s DKW Racer, built from period parts
HRD: Howard Raymond Davies
HRD Motors Ltd was a British motorcycle manufacturer in the 1920s. HRD was later sold to OK-Supreme, who then sold the name to Philip Vincent, who started the Vincent HRD Company Ltd.
JAP: John Alfred Prestwich
JA Prestwich Industries, or J.A.P., was an English engineering company founded in 1895 by John Alfred Prestwich that produced cinematographic equipment and internal combustion engines.
Jawa: Janecek Wanderer
Based in Czech republic, Jawa’s founder, Frantisek Janecek, bought the motorcycle division of Wanderer, in 1929. He used the first two letters of Janecek and Wanderer. Jawa is pronounced (roughly) “Yava.”
|1970 Jawa 500 Buggy (No, I did’nt know either) It’s Bike roots can clearly be seen.
KTM: Kraftfahrzeuge Trunkenpolz Mattighofen
KTM is an Austrian company started in 1934 as a metalworking shop by engineer Hans Trunkenpolz in Mattighofen. KTM began producing motorcycles in 1954.
MV Agusta: Meccanica Verghera
The initials MV stand for Meccanica, or mechanics, and Verghera, the city in Italy where the first MVs were made. The company began as an offshoot of the Agusta aviation company, which was formed by Count Giovanni Agusta in 1923.
MZ: Motorradwerk Zschopau
German for “motorcycle factory at Zschopau.” From 1992 to 1999 the company was called MuZ, an acronym for Motorrad und Zweiradwerk (German for motorcycle and two-wheeler factory).
NSU: The Neckar and Sulm (Rivers)
NSU began as a knitting machine manufacturer in 1873. In 1884, it moved to the city of Neckarsulm, where the river Sulm flows into the river Neckar. The letters N and SU come from these two rivers. another translation of NSU I’ve come across – Neckarsulmer Strickmaschinen Union.
|NSU Super Fox
OSSA: Orpheo Sincronic Sociedad Anónima
The original Ossa company got its start in 1924 making movie projectors for its home market in Spain. The company was known originally as Orpheo Sincronic Sociedad Anónima.
Zündapp: Zünder- und Apparatebau
Zundapp was a major German motorcycle manufacturer founded in 1917 by Fritz Neumeyer that began as an industrial conglomerate that produced detonators. Its name: Zünder- und Apparatebau G.m.b.H.