>Interestingly, "keks" is singular Same thing in Russian. More interestingly, it also happened with other loanwords, even with newer ones: e.g. * бакс = buck

>Interestingly, "keks" is singular Same thing in Russian. More interestingly, it also happened with other loanwords, even with newer ones: e.g. * бакс = bucks (a dollar) -> plural баксы * памперс = pampers (diaper, genericized) -> plural памперсы * чипс = chips (potato chip) -> plural чипсы My guess is that the word was loaned in its plural form, that form was modified to have the "right" ending, and a singular was backformed from that. Like boots -> бутсы (no singular form.. yet).