True if you are wearing your mathematician's or computer scientist's hat. If you are wearing your engineer's or physicist's hat, "O(10)" means "probably >= 5 but <= 50". Context usually makes it obvious which one it is.
Ahgg, leave this poor notation alone. What has it ever done to you?
Expanding to "of order 10" in spoken language.
If the objection is about context dependence, why is nobody going "Would you mind elaborating on the O(10) and what you mean by that? O(10) is the orthogonal group in ten dimensions".