A sequel was a work of fiction that continued where a previous work left off.
In 1893, Mark Twain was asked by a reporter if his next work would be a sequel to A Connecticut Yankee in King Arthur's Court. (TNG: "Time's Arrow, Part II")
In 1953, Douglas Pabst complained that Benny Russell, instead of writing the novella he asked for, had returned with "six sequels to a story I refused to publish in the first place". (DS9: "Far Beyond the Stars")
In 1996, Tom Paris asked Rain Robinson if she had ever seen the sequel to Orgy of the Walking Dead, Bride of the Corpse. (VOY: "Future's End")
Vulcan Love Slave, Part II: The Revenge and Vulcan Love Slave, Volume III were sequels to the holoprogram Vulcan Love Slave. (DS9: "Doctor Bashir, I Presume")