When?

wedding day
the day of a wedding
 
1850s
the decade from 1850 to 1859
 
half life
the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
 
year dot
as long ago as anyone can remember
 
civil year
the year (reckoned from January 1 to December 31) according to Gregorian calendar
 
Islamic calendar month
any lunar month in the Muslim calendar
 
Passion Sunday
second Sunday before Easter
 
first quarter
the first fourth of the Moon's period of revolution around the Earth
 
week from Monday
a time period of a week or more
 
day shift
the work shift during the day (as 8 a.m. to 4 p.m.)
 
quarter-century
a period of 25 years
 
longueur
a period of dullness or boredom (especially in a work of literature or performing art)
 
Low Sunday
the Sunday following Easter
 
air alert
the time period during which military and civilian agencies are prepared for an enemy air attack
 
Fructidor
twelfth month of the Revolutionary calendar (August and September); the month of fruit
 
hereafter
life after death
 
rag day
a day on which university students hold a rag
 
vice-presidential term
the tenure of a vice president
 
quincentennial
the 500th anniversary (or the celebration of it)
 
old age
a late time of life
 
 List More