Toponymy
Le Quesnoy is first attested in forms accompanied by the Latinized name of its alleged founder, called Haymon or Aymond: Haymon Quercitum; (from the Latin ‘quercus' / ‘oak’, a Latin term never imposed in Gaul. Appearing as Caisnetum in romanized charters to try to match the Picard language of the 11th to 14th century and as Haismont-Caisnoit; The Kaisnoit; The Caisnoy; Caisnoit; and Quesnoyt in property titles of the same period (surveys of Hainaut of Cambrai, and Condé).
Quenoy is the Picard equivalent of existing alternate French chênaie.
Picard, as north of the northern Joret line, the group / ca-/ Latin has not evolved as in French quena, formerly Caisne, then Duquesne, ‘oak’ came from the Latin cassinus and may be linked to Fraxinus ‘ash’ of Gallic origin*Cassano. The suffix-oy is the form taken by the Latin suffix -etu(m) in Picard dialect which covers some of northern France and Belgium a few instances elsewhere in the Langue d'oïl etu-(m)'. This suffix is used to denote a set of trees belonging to the same species
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