1- Navajo Language.
The Navajo (Diné) are the second largest Native American tribe of North America. These people still speak their own traditional language although they also speak English fluently.
Navajo people are one of a large family of indigenous peoples of North America known as Athabaskan (or Athabascan). The name of their languages is also Athabascan. The Athabaskan group is the second largest family in North America so there are a big number of languages and speakers. Referring to the territory, only Algic languages cover more area than Athabaskan.
Concretely, Navajo people have lived in the Southwest United States and they speak a Athabaskan language while the majority of Athabaskan languages are spoken in northwest Canada and Alaska.
Navajo language is the most spoken language of the Native American languages. They were more than 168,438 speakers in 2005, and this number has increased with time. A curiosity about Navajo language explains that this language was used during the Second World War as a code in the Pacific War by bilingual Navajo code talkers. So it had an advantage by being a very fast method of encryption never broken by Japanese.
Navajo language has four basic vowels qualities: a, e, i and o. It has two tones, high and low and syllables are low by default. With long vowels these tones combine for four possibilities: high, low, rising and falling.
2. Borrowed words in English.
French (including Anglo-French) and Latin, over 29 % each one, are the two languages from which English borrowed more words. Germanic languages are in third position over 26 % and Greek, over 6% is the fourth language. Other languages, like Spanish or Scandinavian, are over 6% and finally they are over 4% from Proper Names.
Celtic words are almost absent but English syntax was influenced by Celtic languages like the system of continuous tenses, absent in other Germanic languages, which was a cliché of similar Celtic phrasal structures.
3. Which language?
This language is spoken in northern Spain and is an isolate language though geographically it is surrounded by Indo-European Romance languages. It is the last remaining pre-Indo-European language in Western Europe. This language is assumed to have been spoken in the area before the Roman conquests in the western Pyrenees but its origin it’s unknown and all hypotheses on it are controversial and usually they are not accepted by most of linguists.