German here; Never ever heard zenzic. Zen could mean "Zehn" which means ten, where Zic might be an old variant of the suffix -zig which is used to build numbers

German here; Never ever heard zenzic. Zen could mean "Zehn" which means ten, where Zic might be an old variant of the suffix -zig which is used to build numbers between 20-99. Vierzig for example means Forty (Vier = four, plus the suffix). Interestingly it's not as simple for other numbers where the base of the word gets butchered a bit like in english. So as it's "Forty", not "Fourty" it's also "Zwanzig" (20) not "Zweizig". All that makes me wonder if it really ever meant 'squared' or was rather a old form to build number >100. If Neunzig is 90, Zenzig sounds like it could be 100.