1. A way of writing, speaking, or performing something that does not follow proper rules, standards, or conventions
The teacher marked the spelling as an incorrect form.
A professora marcou a ortografia como uma forma incorreta.
2. An alternative version of a word or expression that violates grammatical or linguistic norms
Using 'ain't' is considered an incorrect form in formal English.
Usar 'ain't' é considerado uma forma incorreta no inglês formal.