Where does “iceboxful” come from?

iceboxful (English) comes from English icebox, from English ice, from Middle English is, from Old English īs, from Proto-West Germanic īs, from Proto-Germanic īsą, from Proto-Indo-European h₁eyH- — ice, frost.

Ancestry of “iceboxful”, step by step

iceboxful traces back through two separate lines of ancestry.

via English icebox

StepLanguageWordMeaning
1EnglishiceboxA box or compartment containing ice; A...
2EnglishiceWater in frozen form; Any frozen volatile...
3Middle Englishisice; That which is short-lived like ice; icy...
4Old Englishīsice
5Proto-West Germanicīsice
6Proto-Germanicīsąice
7Proto-Indo-Europeanh₁eyH-ice, frost

via English ful

StepLanguageWordMeaning
1Englishful
Every word from Proto-Indo-European h₁eyH-