/pree'pend'/ (by analogy with "append") To prefix or
add to the beginning.
To attach to the beginning of data. For example, a header is "prepended" to a network packet. Although it sounds correct, prepend is not an English word. It was created to sound like the opposite of "append," which means to add to the end. The correct English word is "prefix;" for example, "the header is prefixed to the packet." See prefix.
Patent 6,876,657 -- System and Method for Router Packet Control and Ordering: Hardware interconnected around multiple packet forwarding engines prepends sequence numbers to packets going into multiple forwarding engines through parallel paths.