err

Etymology 1

From Middle English erren, from Old French errer (“to wander, err, mistake”), from Latin errō (“wander, stray, err, mistake”, verb), from Proto-Indo-European *h₁ers- (“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”).

verb

1. (intransitive, formal) To make a mistake.
   He erred in his calculations, and made many mistakes.
   Artificial tests, then, can hardly err on the side of supplying too many opportunities for one bird to see another perform the act which is the model. 1910, James P. Porter, chapter 2, in Intelligence and Imitation in Birds; A Criterion of Imitation, page 7
2. (intransitive) To sin.
3. (archaic) to stray.

Etymology 2

intj

1. Elongated form of er (“sound of hesitation”).
   Err... what did you just say?