Alan Turing used the term packet to refer to a fixed length (but not necessarily uniform) data structure used to order a larger body of information in order to facilitate computation in a digital computer. It is in his Computing Machinery and Intelligence paper (Mind 59/236):
He wrote the paper before he left the National Physical Laboratory in 1948, where he worked alongside Donald Davies. It was Davies, in turn, who introduced packet in computer networking to denote, well, what we call packets (but not datagrams) today. (And this is where, in computer networking lore, the story begins.) Davies recalls that "after disc