When you add 2+2 and get 5, this is an example of a situation where you err.
I erred in turning onto the dead-end street.
Origin of err
- Middle English erren from Old French errer from Latin errāre to wander ers- in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition
- From Middle English erren, from Old French errer (“to wander, err, mistake”), from Latin errō (“wander, stray, err, mistake”, verb), from Proto-Indo-European *ares- (“to be angry, lose one's temper”). Cognate with Old English eorre, ierre (“anger, wrath, ire”), Old English iersian (“to be angry with, rage, irritate, provoke”), Old English ierre (“wandering, gone astray, confused”).