Shortest possible ambiguity
I'm procrastinating cleaning up an essay, so instead it seemed worthwhile making a short observatory blog post - one ambiguity in English that has come up a few times for me, is often missed, but also is due to a single letter word: 'a'.
An example of the ambiguity is the following question: "When rolling a normal die (faces 1, 2, 3, 4, 5, 6), what is the probability that a number is the result?". Unless you're trying to find corner cases ("it might get stuck on an edge!" - seriously, ignore these, the point still stands), your answer will either be "1/6" or "100%", and they're both right.
The two interpretations can be thought of as: "...what is the probability that a particular single number (e.g. '5') is the result?", in which case, it's 1/6. The other is: "...what is the probability that the result will be in the set of things we classify as 'numbers'?", in which case 100%. The second may seem rare when everything is a number, but consider an alternative: "When rolling a die (faces: 1, 2, 3, A, B, C), what is the probability that a number is the result?", you'd probably say "50%".
The odd thing is, while 'particular' (or maybe 'given' or 'specific') can be used in English to indicate the first alternative, I don't know if there's a good single word for the second. The first that comes to mind is 'any': "What is the probability that any number is picked" - however unfortunately this also has the ambiguity that 'a' had - if asked the original question, I'd guess most people would still say "1/6". Maybe 'indeterminate' works, although it's uncommon so likely to still cause confusion. You could try rearranging the sentence: "...what is the probability that the result is a number?", which seems much clearer, but I'd assume that some (a lot fewer) people would say "1/6".
That's all, short update this time, I should actually start working on the essay. If anyone knows a good word to disambiguate (in the non-'particular' direction), let me know! But remember, even a single letter word can have vastly different, valid, interpretations, and it's quite easy to use one and not even realise others will interpret it as the other [for the context: a few programming contest problems have suffered this exact issue in the past].