When?

day
the period of time taken by a particular planet (e.g. Mars) to make a complete rotation on its axis
 
phallic stage
(psychoanalysis) the third stage in a child's development when awareness of and manipulation of the genitals is supposed to be a primary source of pleasure
 
watch
the period during which someone (especially a guard) is on duty
 
cold spell
a spell of cold weather
 
Regency
the period from 1811-1820 when the Prince of Wales was regent during George III's periods of insanity
 
elapsed time
the time that elapses while some event is occurring
 
leisure time
time available for ease and relaxation
 
Eolithic Age
the earliest part of the Stone Age marked by the earliest signs of human culture
 
baseball season
the season when baseball is played
 
Feast of the Unleavened Bread
(Judaism) a Jewish festival (traditionally 8 days from Nissan 15) celebrating the exodus of the Israelites from Egypt
 
Whitsun Monday
the day after Whitsunday; a legal holiday in England and Wales and Ireland
 
midafternoon
the middle part of the afternoon
 
Armistice Day
a legal holiday in the United States; formerly Armistice Day but called Veterans' Day since 1954
 
Victoria Day
a public holiday in Canada on the Monday on or before May 24th
 
incumbency
the term during which some position is held
 
Quinquagesima Sunday
the Sunday before Ash Wednesday (the beginning of Lent)
 
academic year
the period of time each year when the school is open and people are studying
 
youth
the time of life between childhood and maturity
 
24/7
uptime is 24 hours a day 7 days a week
 
half-term
a short vacation about halfway through a school term
 
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