There are 3 theories on how Kuala Lumpur got it's name.

The first is that Kuala Lumpur got its name from the Hakka word "Lampang" which means "muddy uncleared forest".  Kuala Lumpur was first established when the swampy land beside the Gombak and Klang river junctions was cleared, and it became known as Kuala Lampa, and later as Kuala Lumpur.

The second version is explained by Kuala Lumpur's location at the junction between Sungei Gombak and Sungei Klang. 

In the Malay language, Kuala means a junction between 2 rivers, and Lumpur means muddy. Hence, Kuala Lumpur literally means "muddy river junction." 

The third version is that the place was originally called Pengkalen Lumpur or the "muddy jetty." Klang was originally known as Pengkalen Batu or stone jetty, and the upstream jetty was named Pengkalen Lumpur to differentiate between the two jetties. The explanation assumed that the Chinese then shortened the original name to Kalen Lumpur and then into Kuala Lumpur.