The Nunchuk is the main attachment to the Wii Remote. It consists of a C and Z button and an analog stick. Several Wii games require that a Nunchuk be connected to the player's Wii Remote in order to function, including New Play Control! Pikmin and New Play Control! Pikmin 2. A Nunchuk has a built-in motion sensor, like the Wii Remote.
The Nunchuk is named after nunchaku due to resembling them when used with a Wii Remote.