Definition of soldier for Students. : a person in military service and especially an enlisted person who is in the army.
Zeitgeist is defined as the spirit of a generation or a period of time. An example of zeitgeist is the free love and progressive thinking of the 1960s. the spirit of the age; trend of thought and feeling in a period. Origin of zeitgeist.
Zeitgeber time (ZT): A standardized 24-hour notation of the phase in an entrained circadian cycle in which ZT 0 indicates the beginning of day, or the light phase, and ZT 12 is the beginning of night, or the dark phase.or most animals, the timing of sleep and wakefulness under natural conditions is in synchrony with the circadian control of the sleep cycle and all other circadian-controlled rhythms. Humans, however, have the unique ability to cognitively override their internal biological clock and its rhythmic outputs.