device:  A device is something which has been devised – which, etymologically speaking, amounts to ‘something which has been divided’. For ultimately devise and divide come from the same source. The noun device comes in the first instance from Old French devis ‘division, contrivance’ and latterly (in the 15th century) from Old French devise ‘plan’, both of which were derivatives of the verb deviser ‘divide, devise’ (source of English devise ).
This in turn came from Vulgar Latin *dīvisāre, a verb based on the past participial stem of Latin dīvidere, source of English divide. The semantic development by which ‘divide’ passed to ‘contrive’, presumably based on the notion that dividing something up and distributing it needs some planning, happened before the word reached English, and English device has never meant ‘division’.
late 13c., from Old French devis "division, separation, disposition, wish, desire; coat of arms, emblem; last will," from deviser "to divide, distribute" (see devise). Sense of "method by which something is divided" arose in French and led to modern meaning.
1. The device had been used operationally some months previously.
2. The device exploded, throwing Mr Taylor from his car.
3. The device can discriminate between the cancerous and the normal cells.
4. The built-in safety device compensates for a fall in water pressure.
5. The device plugs into one of the laptop's USB ports.