Sleeper
Part of speech: noun
Definition: Someone who sleeps. A saboteur or terrorist who lives unobtrusively in a community until activated by a prearranged signal; may be part of a sleeper cell. A railroad sleeping car. A horizontal wooden or concrete structural member that supports and ties together railway lines. Something that achieves unexpected success after an interval of time. A goby-like bottom-feeding freshwater fish of the family Odontobutidae. Also "sleeper goby." A type of pajama for a person, especially a child, that covers its whole body, including their feet. A structural beam in a floor running perpendicular to both the joists beneath and floorboards above. An automobile which, not too quick out of the factory has been internally modified to wretched excess, while retaining a mostly stock appearance in order to fool opponents in a drag race.
Example sentence: A work of fiction is conceived very much the same way as a dream occurs in the mind of a sleeper.
Slumberer
Part of speech: noun
Definition: One who slumbers; a sleeper.