What does error mean?
An error is a mistake — something done, believed, or calculated incorrectly. It is among the most versatile words for human fallibility, covering everything from a slip of the tongue to a flawed scientific assumption. Beyond everyday use, error has precise technical senses: in statistics and measurement it denotes the gap between an observed value and the true one (the margin of error), and in computing it signals any condition that prevents software from running correctly, giving rise to familiar phrases like 'error message' and 'runtime error'. The word is neutral in tone; unlike 'blunder' or 'gaffe', calling something an error implies no particular embarrassment, which is why phrases such as 'human error' appear so often in official reports. Its derivatives include erroneous (containing mistakes) and errorless (free of them). From trial and error to margins of error, this word names not just our failures but the very process by which we learn from them.
A mistake or incorrect action, belief, or judgment.
"Casting doubt on the findings, the auditor identified several accounting errors."
Often used in formal and official contexts, as in 'errors and omissions'.
The difference between a measured, observed, or computed value and the true value.
"Repeated measurements reduced the experimental error to under one percent."
In computing, a condition that causes a program or system to fail or behave unexpectedly.
"The application crashed with a fatal runtime error."
Regular plural; used freely in both countable senses (individual mistakes) and technical contexts (sources of error).
"Most accidents are attributed to human errors in judgment."
The word error once carried a moral sting — in Middle English it could simply mean sin — before science claimed it as the honest measure of how far we fall from the truth.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of error
Error comes from the Latin errare, meaning 'to wander' or 'to stray', with the noun error literally signifying 'a wandering' — figuratively, a straying from truth or correctness. English borrowed it directly from Latin via Old French in the medieval period, and it was established by the time of Middle English. The same root gives us err, erratic, errant, and erroneous, all preserving the underlying image of wandering off course. The word long carried moral and religious weight, denoting sin or false doctrine, before its modern technical senses developed.
Related word forms
How error is actually used
Error is neutral-to-formal in register and common in both everyday and technical writing. In computing and engineering it is often paired with codes ('error 404'). Unlike blunder or gaffe, it does not necessarily imply embarrassment.
Easily confused with error
An errand is a short trip to carry out a task (e.g. going to the shop), while an error is a mistake.