Monday / Mon. = poniedziałek

Meatless Monday—the modern

Source: http://business-ethics.com/2010/11/08/1924-arguing-for-meatless-mondays/

poniedziałek

Monday , Mon. (abbreviation) = poniedziałek

English sentence and Polish translation

It can wait until Monday. = To może zaczekać do poniedziałku.