Name origins

Meowth's name in Japanese is written which is translated into "Ni-ya-su"- where the "su" stands in for the "th" sound. Also sometimes referred to as "Nyarth". The name originates from the Japanese sound of a meowing cat ("Nyaa~") and the last sound in the English word for mouth. Respectively, the English translation becomes "Meowth". The idea of Meowth and Mouth is played on extensively in the anime where Team Rocket's Meowth makes puns referring to his mouth. (That and he talks an awful lot). I sometimes wonder if the name also comes from a noisy cat. A few names from other languages:

German: Mauzi

French: Miaouss

Korean: Naong

Chinese (Taiwan): Miao Mao

Chinese (Hong Kong): Miao Miao Guai