Where does “daylength” come from?

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

  1. period of daylight; photoperiod

Ancestry of “daylength”, step by step

daylength traces back through two separate lines of ancestry.

via English length

StepLanguageWordMeaning
1EnglishlengthThe distance measured along the longest dimension...
2Middle Englishlengthelength
3Old Englishlengþulength
4Proto-Germaniclangiþōlongness, length
5Proto-Germaniclangazlong
6Proto-Indo-Europeandlongʰoslong

via English Day

StepLanguageWordMeaning
1EnglishDayderived from a medieval diminutive of David
2Middle Englishdayday; daylight, sunlight; epoch, age, period
3Old Englishdæġday, daytime
4Proto-West Germanicdagday
5Proto-Germanicdagazday; name of the D-rune
6Proto-Indo-Europeandʰegʷʰ-to burn; warm, hot
Every word from Proto-Indo-European dlongʰos