"klucz" means "key", in English

Here is a Gaelic-English dictionary:

MacBain's Dictionary - Section 23
MacBain's Dictionary - Section 23
iuchair
iuchair = a key,
Irish eochair,
Early Irish eochuir,
Manx ogher,
Welsh egoriad, key, egor, agor,
http://www.ceantar.org/Dicts/MB2/mb23.html

klucz - Polish-English Dictionary
klucz key. ...
http://glossword.info/term/320,93,xhtml