Given the task definition and input, reply with output. Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.

In French, if I want to quantify a very small amount of time (but not fixed: it can be 5 ms or 0.1 ms) I can use a pouieme. Is there an equivalent in English? I'm not looking for an expression but for a standalone word. EDIT : In fact, I need to create a c++ class which will measure time and be equal to a 1/600s. In French, pouieme is a cute word which can means a very small but undefined amount of time. The issue is that I must write english code and that's why I would like to find a standalone equivalent.

A blink of an eye and a split second come to mind. Edit: If you insist on a single word, you'll have to go with an instant, or get creative and change the sentence structure to accommodate a different part of speech, like momentar(il)y.