Device
Related: technique - literary technique - plot device
Usage note: Device, contrivance. Device implies more of inventive power, and contrivance more of skill and dexterity in execution. A device usually has reference to something worked out for exhibition or show; a contrivance usually respects the arrangement or disposition of things with reference to securing some end. Devices were worn by knights-errant on their shields; contrivances are generally used to promote the practical convenience of life. The word device is often used in a bad sense; as, a crafty device; contrivance is almost always used in a good sense; as, a useful contrivance. --Wiktionary [Sept 2006]
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