Dechy () is a commune in the Nord department in northern France.
The town has been named, Diptiacum in 899, (Cartulary of Saint-Amand, Miroeus), Diptiacum in 906, Diciacum in 1097, Diptiacum in 1107, Dichis in 1181 (Chronique Gislebert), Dici in 1205
It probably comes from an old *Deppiacum, based of the gallic name Deppios followed from the suffix -acum (from the gallic -acon) of location and property, with the global meaning ë property, farm of Deppios û. The suffix -(i)acum has generally finished as -y in the North (-ecque in the previous dutch speaking area and -eke in flemish), the plural form, appeared later -iacas to -ies.
The archeological statistics of the Nord departement of 1867 indicate: