In the R&K standard, NREM sleep was divided into four stages, with slow-wave sleep comprising stages 3 and 4. In stage 3, delta waves made up less than 50% of the total wave patterns, while they made up more than 50% in stage 4. Furthermore, REM sleep was sometimes referred to as stage 5.
Freebase(0.00 / 0 votes)Rate this definition: Turret. In architecture, a turret is a small tower that projects vertically from the wall of a building such as a medieval castle. Turrets were used to provide a projecting defensive position allowing covering fire to the adjacent wall in the days of military fortification.
bastion. n. 1. (Fortifications) a projecting work in a fortification designed to permit fire to the flanks along the face of the wall. 2. any fortified place. 3. a thing or person regarded as upholding or defending an attitude, principle, etc: the last bastion of opposition.