Quote Originally Posted by chaika View Post
you will not likely ever find a word "without a root". But here's one without a prefix: объект.
Quote Originally Posted by diogen_ View Post
Since I can't recall such a prefix as "ад" in Russian, the word "адъютант" is another example.
perhaps it needs to be pointed out that объект is a borrowed word in Russian, therefore strictly speaking it's not Russian
basically words of Latin origin whos stem starts with j and is preceded by a prefix, in Russian will be spelled with the hard sign

injection - инъекция
conjunctivitis - конъюктивит
subject - субъект
and
object - объект

Adjutant - адъютант

adjutant comes from the Latin adjutans, present participle of the verb adjuvare, "to help"

and ad- seems also a prefix like in the words adjective, adverb, admit (these stems with other prefixes: subjective, proverb, permit)

so somehow the rule of the hard sign after prefix is maintained with at least these borrowed words as well

genuinely non-separating i can't think of, are there any?