A small pack or package; a little bundle or parcel
(nautical) Originally, a vessel employed by government to convey dispatches or mails; hence, a vessel employed in conveying dispatches, mails, passengers, and goods, and having fixed days of sailing; a mail boat. Packet boat, ship, vessel (Wikipedia).
(botany) A specimen envelope containing small, dried plants or containing parts of plants when attached to a larger sheet.
(networking) A small fragment of data as transmitted on some types of network, notably Ethernet networks (Wikipedia).