daylength (English) comes from English length, from Middle English lengthe, from Old English lengþu, from Proto-Germanic langiþō, from Proto-Germanic langaz, from Proto-Indo-European dlongʰos — long.
daylength (English): period of daylight; photoperiod
Definitions
period of daylight; photoperiod
Ancestry of “daylength”, step by step
daylength traces back through two separate lines of ancestry.