The linguistic database was a compiled collection of known languages. They were used by the Vulcans as early as 2151, when they shared samples of Klingonese with United Earth Starfleet. (ENT: "Broken Bow") The Enterprise later maintained its own database. (ENT: "Fight or Flight")

In 2161, shortly before returning to Earth to decommission Enterprise, Ensign Hoshi Sato figured she would need a week to purge the linguistic database. (ENT: "These Are the Voyages...")

The linguistic database played a role in Starfleet finally managing to communicate with the Tamarians. (TNG: "Darmok")

Borg drones also maintained a linguistic database, without which they were unable to assimilate information. (VOY: "Drone")