A third officer is an officer aboard a starship who is fourth in line of command of the vessel after the commanding officer, first officer, and second officer. In Starfleet the position was sometimes held by the security chief, tactical officer, or chief engineer, and was typically filled by a lieutenant commander or lieutenant.
In 2257, Lieutenant James T. Kirk attempted to contact the third officer of the USS Farragut after his attempts to contact Captain Garrovick, First Officer Tolan and the ship's second officer had proven unsuccessful in the wake of an attack on the Farragut by the dikironium cloud creature. (TOS - My Brother's Keeper novel: Constitution)
External link[]
- Third officer article at Memory Alpha, the wiki for canon Star Trek.