error
a mistake or departure from correctness
Root
- err / errare: wander, stray, or go off course
Other words with the err / errare root
- aberrant: departing from the usual course
- aberration: a departure from what is normal or expected
- err: to make a mistake or go wrong
- errant: wandering, straying, or behaving wrongly
- erratic: irregular or unpredictable
Error is the familiar doorway: the mind or action has gone off course.
One small error changed the answer even though the method was right.