EN
In some Polish words, the final -aj is pronounced as [ej], e.g. daj > dej, dzisiaj > dzisiej, tutaj > tutej, wczoraj > wczorej, bodaj > bodej. This pronunciation is considered to be of dialectal or regional origin. The present author claims that the development -aj > -ej is not a regular sound change, but is to be accounted for by what he calls irregular sound change due to frequency.