ploy: 17th century. originally Scots and northern English in the senses [pastime,] [escapade,] and [a trick] ): of unknown origin. The notion of ‘a calculated plan’ dates from the 1950s.
employ :late Middle English (formerly also as 'imploy'): from Old French 'employer', based on Latin 'implicari' ‘be involved in or attached to,’ passive form of implicare (see imply ). In the 16th and 17th cent. the word also had the senses [enfold, entangle] and [imply,] derived directly from Latin .