A compass is a device used for navigating by the means of a magnetic needle.
Jonathan Archer gave his first officer T'Pol an antique compass from the early 20th century, as a present, for her first official day of duty aboard Enterprise in 2154. Upon giving it to T'Pol, Archer told her that it "should help keep [her] pointed in the right direction." (ENT: "Borderland")
In 2370, upon seeing a statue from the D'Arsay, Jean-Luc Picard mentioned to William T. Riker that the four cardinal compass directions seen on the statue was a common theme in many cultures, possibly meaning finding a path, movement or crossing a boundary. (TNG: "Masks")
One of the easiest ways to construct a compass was to place a magnetized piece of metal in a solution so that it floated. Miles O'Brien created a primitive compass with this method while marooned with Benjamin Sisko on a planet in the Orellius system. (DS9: "Paradise")
Upon being awakened from cryogenic stasis in 2371, Amelia Earhart found that her compass wasn't working anymore. (VOY: "The 37's")
Among the tools in Benjamin Sisko's lightship was a sextant and a compass. (DS9: "Explorers")
In 2372, B'Elanna Torres used the Caretaker's remains as a "compass" to possibly locate his mate Suspiria. (VOY: "Cold Fire")
In 2373, B'Elanna Torres suggested trying to amplify and polarize the instability of the Barzan wormhole, so it would reappear. Janeway referred to the polarization of the wormhole to using a magnet to attract a compass. (VOY: "False Profits")
In 2374, a hologram of Leonardo da Vinci exclaimed to Kathryn Janeway while stranded together on a planet in the Delta Quadrant that "even Theseus could not negotiate this labyrinth!" to which Janeway replied "not without a compass." (VOY: "Concerning Flight")
