Eclipse
An eclipse is an event caused by a celestial object casting a shadow onto another.
In 2367, an eclipse occurred on Banea, a planet in the Delta Quadrant. Professor Tolen Ren and his wife, Lidell, witnessed it.
She remarked to Tom Paris in 2371 that when the eclipse occurred, it was the last time he treated her like a wife instead of a mere friend. She also expressed her uncertainty as to why it had excited him at the time. Paris later recalled this conversation when Tuvok asked him what he remembered of the evening. (VOY: "Ex Post Facto")
The planet Lyrek had twin moons that cast a double eclipse shadow on an area of its surface once every seven years. The ancient Promellians constructed a necropolis there to inter their dead. (DIS: "Under the Twin Moons")
"Eclipse" was the working title of DS9: "Strange Bedfellows".
"Solar and lunar eclipses" are also alluded to in a schematic overlaid on the Apollo Lunar Module segment of the Enterprise opening credits.
A class of starships (β) in Star Trek Online is also called "Eclipse class", named after a prototype ship.