The aim of this paper is to conduct a diachronic analysis of the Polish word rżysko ‘stubble’, whose root retains the primary designation of rye, namely reż ‘rye, obs.’. Although this noun was ousted by żyto ‘rye’, a derivative of the verb żyć ‘to live’, its cognates are still used in many Slavic and Germanic languages, e.g. Russian rožь (рожь) ‘rye’, and English rye. The paper presents other cognates with a view to contrasting the English word rye with its obsolete Polish cognate reż and understanding the evolution of both words. For this purpose, the study seeks to identify the sound changes responsible for the discrepancy between the Polish-English cognates which developed from *rughi-. The derivative rżysko ‘stubble’ has been analysed in the context of other nomina loci as well as the semantic change which affected the word. It is suggested that the phenomenon exemplified by rżysko can be referred to as a root archaism.