[Lucid:]

bulbapedia.bulbagarden.net has a page on every pokemon, and their english names and Japanese names. it gives name orgins, too.
"Pikachu is a combination of ピカピカ pikapika which is Japanese onomatopoeia for sparkle and チューチュー chūchū which is the sound of squeaking. It may be named after the pika, a lagomorph, but this is less likely. "Pika" also means "quick" in Finnish."