Etymology is the study of the origin and meaning of words. This word itself derives from the Greek "etumon" meaning true and "logos" meaning word. Thus etymology is the true meaning or literal sense of a word. Xenophobia derives also from the Greek "xenos" meaning strange and "phobos" meaning fear. We humans are a unique species that are the sole possessors of a language instinct. Chomsky deserves the credit for clearly enunciating this obvious fact that developmental neurologists and other scientists including the social pseudo-scientists totally missed. Despite all the hoopla that PBS, the National Enquirer, the New York Times, the Washington Post, National Geographic science trash misinformation that people receive, our cousins the gorillas, chimpanzees and parrots do not have true linguistic ability. Have you ever wondered that a two year old who cannot clean its rear end and pees in the worn clothes, can without formal teaching pick up any language heard at home and communicate meaningfully while unable to handle a knife and fork or tie shoelaces?
The other interesting fact is that a newborn or even a few months old child has no fear of strangers. A few months later it is wary of strangers and cries often no matter how gentle and caring the stranger's initial approach is. This xenophobia is a natural instinct and the cry an alarm to attract the attention of parents to initiate a rescue. Thus language and initial xenophobia are programmed in our genes. It is but a short step from these self-preserving instincts to make the leap to racism and bigotry. Once again the roots lie in language.
Ancient Hebrew and Arabic have two unusual features distinguishing them from the Indo-European language family. First they are written from right to left and second there is a conspicuous absence of notations for vowels in the scripts that they use. Thus the ancient Canaanite god Moloch (malek in Hebrew) to whom human sacrifices were offered is written as MLCH in the letters of the two languages. The Sanskrit speaking Indian Aryan culture found the language of the Middle Eastern Semites incomprehensible and the absence of vowels suggestive of a more primitive culture. They were unable to speak Sanskrit (Sanskrit means perfectly made and thus Sanskriti denoted a superior culture) and thus the chauvinists coined a derogatory word from their god by calling them "mlechhas" by adding a few vowels to their word. Interestingly after the Islamic conquest of India and the absorption of Arabic words in the local languages, the word "malik" in North Indian languages came to mean god or owner and now is a not uncommon Hindu surname in the North.
Language was a common cause of discrimination the world over, but the favorite tool of Indo-Europeans. The English word barbarian comes from the Greek "barbarikos" meaning incomprehensibly foreign and in fact North Indian languages still have the word "badbadaat" meaning gibberish. What is amusing is that many Western women are given the name Barbara proudly and without understanding its meaning. I am not surprised because in India so-called educated people name their daughters Urvashi, which literally comes from Uru meaning thighs and Vashi the feminine gender word for conqueror. Thus Urvashi means a woman who conquers with her thighs (by what is between them). Again prominent persons name their sons Rahul which literally means impediment. Prince Gautama, later Buddha wanted to renounce the world and when a messenger brought him the news of the birth of his fist child and the male heir and asked him how he should be named, the conflicted prince replied Rahul meaning impediment or obstruction of his cherished goal of renunciation. To me the diagnosis is obvious he was in the throes of severe clinical depression that Prozac could have cured. Another misguided individual of the same ilk was Nanak who abandoned his wife and children and ran away possibly to Mecca with a band of Sufis. It was an era when the Bhakti Marga was fashionable thanks to the superb poems of Kabir, Surdas and Mira. Contrast that to other prophets who were not satisfied with one wife but instead of abandoning her chose to have more simultaneously as well as serially.
Islam was and is a religion of the Arabs. Thus prayer can be done only facing Mecca. The Koran must be read and recited only in Arabic and it is incumbent upon even non-Arab Muslims to make the Hajj to the Kaaba in Mecca. Catholicism used to insist on saying the mass in Latin but they changed with the times. A religion centered in specific geographic locale that decides to proselytize and convert, often has a problem with other ethnic and linguistic groups who succumb to the pressure. The solution is to make them honorary members of the inclusive privileged group. When apartheid South Africa needed Japanese commerce they made them honorary whites. The Spanish Inquisition gave Sephardic Jews three choices, convert, be burnt alive or emigrate stealthily. Many rich and poor Jews converted to preserve their wealth or because they were desperate just like similar Hindus in India after the Islamic conquest. The Christians were reluctant to fully accept the new converts and often insisted that these maranos would have to take distinctive surnames derived from fruit trees - thus names like Pereira also seen amongst the Indian converts by the Portuguese who ran their own inquisition. Anyway the Arabs made these new Muslims honorary Arabs and called them "mawla" whose plural is "mawalis". I don't know whether the intention was like that of the Spanish Christians to always remind them as in the movie "Sujata", Tu hamaari beti jaisi hi hai. Anyway in the present North Indian languages "mawali" has come to mean riffraff, undesirable criminal or antisocial persons. I have been unable to determine whether the discrimination was the original intent of the Arabs who coined the category, or is the new meaning now attributed on the basis of Indian Hindu prejudice towards Muslims in general or converts in particular.
I find it fascinating to trace the genealogy of words as in Panini's Dhatupadaand my old review of The Mendelian Genetics of English and amusing that the meanings change with time as in from the gay nineties to the gay today.