Where does “Hallowe'ek” come from?

Hallowe'ek (English) comes from English week, from Middle English wyke, from Old English wīc, from German witz, from Middle High German witz, from Old High German wizzi, from Proto-West Germanic wītī, from Proto-Germanic witją — to see.

Ancestry of “Hallowe'ek”, step by step

Hallowe'ek traces back through two separate lines of ancestry.

via English week

StepLanguageWordMeaning
1EnglishweekAny period of seven consecutive days; A period of...
2Middle EnglishwykeAlternative form of wikke; Alternative form of...
3Old Englishwīcdwelling place, abode; abode, dwelling-place;...
4Germanwitzjoke
5Middle High Germanwitz
6Old High Germanwizzi
7Proto-West Germanicwītīpunishment
8Proto-Germanicwitjąknowledge; reason; sense; understanding; wit
9Proto-Germanic*witaną
10Proto-Indo-Europeanwóydeto have seen, to know
11Proto-Indo-Europeanweyd-to see

via English Hallowe'en

StepLanguageWordMeaning
1EnglishHallowe'en
Every word from Proto-Indo-European weyd-