Real Dictionary

error
a mistake or inaccuracy, as in action or speech [...]
a quantity or amount considered in relation to or measured against another quantity or amount [...]
a rigid usually straight length of metal, wood, etc, that is longer than it is wide or thick, used esp as a barrier or as a structural or mechanical part [...]
variable noun: An error is something you have done which is considered to be incorrect or wrong, or which should not have been done.