noun
long day (especially in spring)
Refers to the lengthening daylight hours, particularly associated with spring. Often used in poetic or literary contexts. Compare with 夜長 (long autumn night).
See also: 夜長
春の日永、縁側でうたた寝をするのが好きだ。
On a long spring day, I like to doze off on the veranda.
日永の頃になると、夕方まで明るい。
Around the time of long days, it stays light until evening.
夜長 refers to the long nights of autumn, while 日永 refers to the long days of spring.
Compound of 日 (hi, 'day') and 永 (naga, 'long'). The reading ひなが is a rendaku form of ひ (hi) + なが (naga).