the delayed impact of a persuasive message, as through marketing
noun on an aircraft, a seat designed to recline nearly horizontally, like a bed; on a train, a small sleeping compartment
noun 1. a seat, as on an airplane, that can be extended horizontally to permit sleeping.
- Sleeper terrorist
noun 1. a terrorist who is not currently active but assumes a guise in order to be in position, unsuspected, for future terrorist activities
- Sleep hygiene
noun 1. the habits conducive to getting the right amount and quality of sleep