Last night I heard a BBC programme relayed through ABC NewsRadio. The crew were discussing someone's computer-generated prediction that in 2009 the vocabulary count for English would reach one million. As the guy being interviewed pointed out, the question is: How do you define "word"? He gave the example "is, are, was". I think it's fairly easy to accept that the various parts of verbs and plurals of nouns can be excluded. There's only one instance of "case" left in English, as far as I know; that's the personal pronouns, as in I, me, us, we, etc. That can get tricky, with argument about whether they rate as unique words, whether the old forms "thou" and "ye" and so on can still be counted. Then there's the issue of whether words of the type "my" and "mine" are genitive cases of pronouns or "possessive adjectives". I support the former view. Same goes for who and whom and myself. Pronouns all. The grammar-meddlers who say otherwise can visit the taxidermist for a good stuffing. Anyway, there are so few words in this category that we can ignore them in this context.
What is harder is dealing with words like "table". Apart from the furniture it denotes a collection of figures or words organised in a rectangular array for comparative or computational purposes. Unlike with "bear" the beast and "bear" the deed, these aren't completely separable etymologies with an accidental coincidence in modern spelling. The figurative use of "table" to describe the written data derives from the use of table-tops for ciphering and writing. I.e. actually writing on wood with chalk or drawing in sand spread on the table. So, are these two separate words or two connotations of one word? (Discuss in a ten-thousand word dissertation and have it on my desk by three-thirty p.m. on Monday.)
On firmer footing is the issue of loan-words. I think I've found an original slant on this. I've heard a lot of argument over many years about when a word imported from a foreign language is truly an English word. I think the easiest way to settle this bugbear is to apply a benchmark usage test. I'd propose that if a word can be understood by most randomly-chosen English-speakers that you say it to then it has become an English word. A good example is the vocabulary we've acquired from the Western Asiatic disturbances of the past thirty years. This includes ayatollah, fatwa, fedayeen, imam, jihad, madrassa, muezzin, mullah and mujahideen. Shahid (martyr) is probably familiar to people who take a particular interest.
"Allahu akbar" is a phrase which everybody on Earth has heard and which, if accepted as intelligible to most English-speakers, can now reasonably be called part of the English language. It's an example of a phrase which denotes a cultural context or can be used in a narrative. For example, if you're telling a story about a political rally or other event involving Muslims and you say or write, "The crowd were chanting 'Allahu akbar' ", you don't really need to explain its meaning. Having said that, I'll now dispute its meaning...
Although a phrase such as "Allahu akbar" can be understood in essence when translated into other words more familiar to English language speakers, there is a tendency to try to exoticise foreign-origin phrases or even to try to make them sound simplistic or awkward. This is, I suspect, to emphasise the weirdness of the foreign language or of the foreigners themselves. This is where translation occurs at a literal level without conveying a correct semantic impression. The usual translation given for "Allahu akbar" is "God is great" or "God is the greatest". This sounds to an English speaker like a rather crude choice of words; as though "God" was the name of a brand of cola drink. A more reverential tone would be struck by translating it as "The Lord is Supreme". A similar case is "Al Qaeda". This is usually translated as "the base". It may well be the word used in Arabic for "base" as in "base of operations" or "military base". However, to give a more significant and accurate translation to English, I feel that "foundation" is the right word, (even though there is another Arabic word meaning "foundation" as in a developmental institution). Thus, "Al Qaeda" would be "The Foundation".
To finish; an interesting example on these lines is the German word panzerkampfwagen. This is usually rendered as "tank" in English. The complete word can be comfortably translated as "armoured fighting vehicle." Someone wanting to make German look dopey could literally translate this as "panoplied struggle wagon". (That phrase reminds me of the embellished panel vans that Australian teenagers used during the 1970's and 80's for extra-domestic inter-gender relationship development. That's another story...)