Jefferies tubes - Internal maintenance conduits that are used to provide crew access to various ship's systems.
jeffries tube - Internal maintenance conduits that are used to provide crew access to various ship's systems.
Jem'Hadar - A race from the Gamma quadrant that was genetically engineered by the Changelings.
jfs47 - A system in the Pi Canis Sector
jiro - A first name. Most notably is Ambassador Jiro Sugihara of Starfleet who is the liason to the Diplomatic Corps.
Jiro Sugihara - In Star Trek Online he is an Ambassador and your contact for the Federation Diplomatic Corps.
JS - Jam Sensors (Science Ability)
jump - The action of pushing off a surface into the air.