A linguistic database, linguistics bank, linguistic files, or foreign language bank was a compiled collection of known languages.
The Vulcans maintained such a database as early as 2151, when they shared samples of Klingonese with the United Earth Starfleet. (ENT: "Broken Bow") The Enterprise later maintained its own database, which could be tied in with the universal translator. (ENT: "Fight or Flight")
When Hoshi Sato suffered from hallucinations while in a pattern buffer, she claimed that crewman Baird had translated a complex language, even though he knew nothing about the ship's linguistic database. (ENT: "Vanishing Point")
While investigating the alleged murder committed by Montgomery Scott, the term "Redjac" came up as a piece of evidence. In effort to uncover its meaning, Spock consulted the linguistic bank to define the word, where it was determined that the term did not exist in the linguistics bank. To expand his efforts, Spock had the computer scan all other banks, where it was determined that the term was a proper name, sourced from Earth's 19th century English language, and defined as the "Nickname for mass murderer of women," synonymous with the name "Jack the Ripper". (TOS: "Wolf in the Fold")
Shortly after this, the Enterprise encountered the Nomad space probe, that when attempting to communicate, it sent a formula, specifically a mathematical message in effort to request language equivalence. Kirk acknowledged the request and had Spock tie in the ship's universal translator to the communication channel and let the probe "take it at their own speed." (TOS: "The Changeling")
During the USS Enterprise's visit to Sigma Iotia II in 2268, Lieutenant Commander Montgomery Scott had difficulty understanding the native slang spoken by Bela Oxmyx. After completing a transmission with Oxmyx, who just asked for "a hundred of these fancy heaters you've got", Scott asked Lieutenant Hadley to check the language banks and find out what a heater is. (TOS: "A Piece of the Action")
Following Voyager's discovery of the Vaadwaur in 2376, Neelix consulted his personal database, specifically his Talaxian linguistic files of the Old Tongue dialect, in order to find and define the word "Vaadwaur." The computer found the term, described as an "archaic adjective," with several meanings, including "foolish" (primary), "weak-minded", "reckless", "blind."