Source : Webster's Revised Unabridged Dictionary (1913)

Packet \Pack"et\, n. [F. paquet, dim. fr. LL. paccus, from the
   same source as E. pack. See {Pack}.]
   1. A small pack or package; a little bundle or parcel; as, a
      packet of letters. --Shak.

   2. 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}, or {vessel}. See {Packet}, n., 2.

   {Packet day}, the day for mailing letters to go by packet; or
      the sailing day.

   {Packet note} or {post}. See under {Paper}.