noun

• (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).
  "With just the turn of a shoulder she indicated the water front, where, at the end of the dock on which they stood, lay the good ship, Mount Vernon, river packet, the black smoke already pouring from her stacks."
• (botany) A specimen envelope containing small, dried plants or containing parts of plants when attached to a larger sheet.
  "With fresh material, taxonomic conclusions are leavened by recognition that the material examined reflects the site it occupied; a herbarium packet gives one only a small fraction of the data desirable for sound conclusions. Herbarium material does not, indeed, allow one to extrapolate safely: what you see is what you get[…]."
• (networking) A small fragment of data as transmitted on some types of network, notably Ethernet networks (Wikipedia).
• (networking) A protocol data unit of the Internet Protocol.

verb

• (transitive) To make up into a packet or bundle.
• (transitive) To send in a packet or dispatch vessel.
  "[H]er husband / VVas packetted to France, to ſtudy courtſhip, / Under forſooth a colour of employment, / Employment, yea of honour."
• (intransitive) To ply with a packet or dispatch boat.
• (transitive, Internet) To subject to a denial-of-service attack in which a large number of data packets are sent.
  "2007, Committee on Improving Cybersecurity Research in the United States, Toward a Safer and More Secure Cyberspace Typically, one hacker will annoy another; the offended party replies by launching a denial-of-service attack against the offender. These attacks—known as packeting—tend to be of limited duration […]"