Asleep/əˈsliːp/ Definition 1 of 3Pro Tip 1/3Complete Inactivity Describes a person completely at rest, with no awareness of their surroundings. She was so asleep that she didn't hear the thunderstorm. Pro Tip 2/3Time Intensifier Used to emphasize the length or depth of sleep. He's been asleep for ten hours straight. Pro Tip 3/3Peaceful Unawareness Often implies that the sleeping person is untroubled and resting well. The baby is asleep in her crib, dreaming sweetly.