Native word

A native word is a word (or more precisely, lexeme) that was not borrowed from another language, but was inherited from an earlier stage of the language, i.e. a word that is not a loanword.

Comments
Strictly speaking, the term native word can only be relative to some earlier stage of the language. So English hand can be said to be a native word (as opposed to the semantically related manual, a loanword), but only with respect to Old English or Proto-Germanic. At a still earlier time, hand may have been borowed from some other language, i.e. it may be a loanword after all (we have no way of knowing).

Synonym
inherited word

other languages
German Erbwort