Technology / Aviation / Twilight Zone: Long before Rod Serling's tv series was this consumer-lever definition for a glitch in the ADCOCK RANGE, officially called a Bi-Signal Zone. It was a portion of the overlapping area of a beam where the continuous monotone 'on-course' signal became temporarily overlayed with the 'A' or 'N' code signals. Read more here.
Twilight Adjective Synonyms: dusk, sunset, gloaming, sundown, half-light, crepuscule or crepuscle
Zone Noun Synonyms: area, quarter, district, region, sector, section, sphere, belt, territory, province, realm, domain, precinct, bailiwick, department, terrain, circle, locality, locale, turf
Science / Marine Biology / Mesopelagic Zone: Also called the 'twilight zone' of the ocean, this area from 200m to 1000m in depth, is bordered by the photic zone above and darkness below. It's in this zone where you start to see bioluminescence o MORE
Health / Fitness / Target Heart Rate Zone: The number of heartbeats per minute reflecting the exercise intensity that gains the maximum training benefits from an aerobic workout. The formula for obtaining a target heart rate equals 220 minus y MORE