device
noun
an instrumentality invented for a particular purpose
“the device is small enough to wear on your wrist”
“a device intended to conserve water”
something in an artistic work designed to achieve a particular effect
any clever maneuver
“he would stoop to any device to win a point”
“it was a great sales gimmick”
any ornamental pattern or design (as in embroidery)
an emblematic design (especially in heraldry)
“he was recognized by the device on his shield”
Source: WordNet 3.1, Princeton University
