One group of such words has to do with ships and the sea; words like keel, oar, rudder, steer, and mast are shared by almost every Germanic tongue, but not by any other kind of Indo-European speech. Another group of these words deals with war and weapons; words like sword, shield, helmet, bow, king, and knight are all found in almost every Germanic tongue, but in none of their Indo-European kin. The words that name wild things like eel, carp, stork, and bear are also among these odd words; so are a few tame ones like calf and lamb. There are scores of non-Indo-European words that are used daily by English speakers; words like earth, blood, bite, hand, wife, evil, little, sick, bring, run, and house. Among the Germanic languages, these words are found to the north, south, east, and west. A few of these words are shared with the Celtic tongues, but otherwise no other tongue has them. For all of the above-mentioned words, the first roots remain unknown.
Whoever contributed these words left a deep mark on the Proto-Germanic language. Moreover, words such as these are seldom borrowed; words that are used daily for things around the house seldom are loanwords.
Linguists have made several guesses about the origins of these words. Some believe that the Germanic folk of old mixed with some other people; they give the origins of these words the name Folkish, for folk itself is one of these unknown words. Others call the people who first spoke these words the Battle-Axe people; they believe that they can identify the people who gave these words to the Germanic languages from the remains of their refuse and their corded earthenware. Whoever they were, the language they spoke disappeared long ago, and left no tracks other than these words that live on in the Germanic languages.
Yet others say that there was no such people, and that these words do indeed have Indo-European roots, though the form they had of old has been lost. Whether the manner of speaking of the people that brought these words into Germanic had anything to do with the phonetic shifts known as Grimm's first law is also something upon which linguists do not agree.
A number of root words for modern European words are believed to limit the geographical origin of these Germanic influences, such as the root word for ash (the tree) and other environmental references suggest a limited root stream subset which can be localized to northern Europe.
German, Celtic and Slavic are surviving linguistic groups with language traditions that originated outside Indo-European and latinized influences.