In otaku usage, it's come to mean cuter than cute, really... Literally, though, it means loveable, being composed of the Chinese characters "ke" (possible) and "ai" (love). What's kawaii? Cabbits, Pikachu, Skuld, Belldandy, Mokona, SD anything, the Rayearth girls... I suspect kawaii is known to kill in large doses, but it's very hard to resist.