A skeleton crew features a minimal number of crewmen required for starship or space station operations, sometimes fewer. They are often formed during emergencies.
The D5 class variant was capable of operating with a skeleton crew of just four. (ENT: "Marauders")
The final version of the Xindi superweapon was designed to be operated by a skeleton crew. (ENT: "Azati Prime")
In 2268, the USS Enterprise needed a skeleton crew of twenty while using the M-5 computer. (TOS: "The Ultimate Computer")
In 2287, Starfleet Command had the USS Enterprise-A go to Nimbus III, much to Captain Montgomery Scott's dismay as he remarked, "the ship's in pieces and we've got less than a skeleton crew aboard!" (Star Trek V: The Final Frontier)
In 2368, Commander Data suggested a skeleton crew from the USS Enterprise-D could take the Kallisko to a starbase. (TNG: "Silicon Avatar")
In 2369 a skeleton crew operated the space station Deep Space 9 after a aphasia virus infected everyone except Quark and Odo. (DS9: "Babel")
The term was not spoken in the episode but is in the script of the episode.
In 2370, the Enterprise-D was left with only a skeleton crew under the command of Beverly Crusher while the rest of the crew were on the surface of a planet, searching for Data. (TNG: "Descent", "Descent, Part II")
A few weeks later, a skeleton crew was left to run Deep Space 9 during a plasma disruption that forced the evacuation of the station. (DS9: "Invasive Procedures")
After the Reckoning began on Deep Space 9 in late 2374, a skeleton crew remained aboard once the majority of the station's population had left. (DS9: "The Reckoning")