daylight saving time

Short definition from Wiktionary

Noun

1. 1
   The practice in some places of adjusting clocks forward in the spring and back in the fall, usually by one hour, so that the adjustment causes the time to coincide with the greatest period of illumination by the sun over the course of the day.
2. 2
   Alternative form of daylight saving time.
3. 3
   Alternative letter-case form of daylight saving time.