longest day
nounUK /ˈlɒŋ.ɡɪst deɪ/
US /ˈlɔːŋ.ɡɪst deɪ/
The longest day is the day in the year with the most daylight.
We had a picnic on the longest day of the year.
OTHER MEANINGS
2. A day that feels very long because you are busy or waiting.
Waiting for the test results made it the longest day of my life.
3. The day with the most hours of sunlight in a particular place.
In the Arctic, the longest day can have sunlight for almost 24 hours.
4. A day when something important or tiring takes a lot of time.
Moving to a new house turned into the longest day of the summer.