לויצק
'Lutsk (town in northwestern Ukraine)'

ETYMOLOGY

[What is the early German name that Y borrowed?]
Beider suggests that Y borrowed the name not from Polish directly, but from the Silesian dialect of German colonists in Poland - in whose dialect the vowel /u/, borrowed as MHG û, was diphthongized to NHG au. This corresponds to protovowel U₄ in CY Loutsk.
Polish Łuck.

LOyTsK [Yiddishland, Paul Glasser]

CENTRAL

giɛtrɔfn ɔb-ax ᵻn ɬutsk tsvaj bridɛ געטראָפֿן האָב איך אין לוצק צוויי ברידער {Warsaw, Geller 2001: 157}