noun

1. the state of believing what is untrue, incorrect, or wrong
2. a wrong belief; incorrect opinion
3. something incorrectly done through ignorance or carelessness; mistake
4. a departure from the accepted moral code; transgression; wrongdoing; sin
5. 1. the difference between a computed or estimated result and the actual value, as in mathematics
   2. the amount by which something deviates from what is required
6. ☆ Baseball a misplay in fielding or throwing a ball which allows a runner to reach base or to advance to the next base: neither a wild pitch nor a passed ball is an error
7. Law a mistake in judgment or procedure of a court of record, usually prejudicial to one of the parties
8. Philately a flaw in a stamp or stamps from a defect in a printing plate, a difference in color, etc.

Etymology: ME & OFr errour < L error < errare: see err