This familiar colloquialism dates from 1663 according to the OED and was first recorded as chrony. It was originally Cambridge University slang for an associate or intimate friend. It was probably invented by an academic, rather than etymologically derived from the Greek chronos meaning time, with the association of being contemporary. Samuel Pepys, who was a Cambridge man, used it in his famous diary in 1665, using the original spelling chrony. It was Cambridge University’s equivalent to Oxford’s chum. It became something of a tradition that if one was at Oxford, one had ‘chums’ while at Cambridge one had ‘cronies’, and these language protocols are maintained by ‘Oxbridge’ students and graduates to this day. Cronyism, the preferential treatment of one’s friends and colleagues, with pejorative connotations, dates from the mid-20th century and has given rise to some negative associations for the word crony.