device

noun

1. an instrumentality invented for a particular purpose"the device is small enough to wear on your wrist"
2. something in an artistic work designed to achieve a particular effect
3. any clever maneuver"he would stoop to any device to win a point"
4. any ornamental pattern or design (as in embroidery)
5. an emblematic design (especially in heraldry)"he was recognized by the device on his shield"