In Russian it's "ребёнок" (child) and "дети" (children). "Дети" is actually a plural form of now archaic "дитя" and used because... "ребёнок" does not have a pl

In Russian it's "ребёнок" (child) and "дети" (children). "Дети" is actually a plural form of now archaic "дитя" and used because... "ребёнок" does not have a plural form. The funny thing here is that "ребёнок" while not being archic comes from an anchient-russian "робя", which has plural form "робята", which is actually used in modern language too, but meaning can be anything from "boys" to "guys" or any other generalisation of a group of young people (both boys and girls). PS: at the same time you can actually invent a plural for "ребенок" if you want to, but it may be considered as something similar to cockney, but used on purpose in otherwise normal speech.