In general, what does it mean when people say "something is not an option"? It sounds like it means "something is a must". Am I right?
closed as not a real question by MετάEd, tchrist, Mitch, Kris, TimLymington Dec 18 '12 at 18:16
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It depends on the context. It is not an option might mean, it is not an option that is available, so it cannot be done.
It might also mean that something is mandatory (not optional), in which case it must be done.
Perhaps you could expand on your question a little?
Since an option is a choice, if something is not one of the options, it can't be chosen. But if something truly is not one of the possible choices, the phrase is often something is not one of the options.
The phrase something is not an option is often idiomatic, where the something actually could be the outcome, but it is seen as something that should not be considered a wise or desirable choice.
For example, if I were planning to do something extremely important to me--for instance, getting an advanced degree--I might say that failure is not an option. I could fail, but it would not be something I would deliberately choose to do. (Failure in a course of education, of course, is quite literally a possible outcome, as in a failing grade, but it need not be so literal.)