An operative person or thing.
Any of a class of behaviors that produce consequences by operating (i.e., acting) upon the environment.
That operates to produce an effect.
A sedative.
A railroad tie.
A goby-like bottom-feeding freshwater fish of the family Odontobutidae.
A type of pajama for a person, especially a child, that covers the whole body, including the feet.
A sleeper hold.
A heavy floor timber in a ship's bottom.
A nurse shark (family Ginglymostomatidae).
That which lies dormant, as a law.
A bet placed on the gambling table and then forgotten about by the gambler.
An automobile which has been internally modified to excess, while retaining a mostly stock appearance in order to fool opponents in a drag race, or to avoid the attention of the police.
A small starter earring, worn to prevent a piercing from closing.
Someone who sleeps.
Something that achieves unexpected success after an interval of time.
A structural beam in a floor running perpendicular to both the joists beneath and floorboards above.
A spy, saboteur, or terrorist who lives unobtrusively in a community until activated by a prearranged signal; may be part of a sleeper cell.
A railway sleeping car.
The lowest, or bottom, tier of casks.
To mark a calf by cutting its ear.