Double Negative
WordNet
noun
(1) A grammatically substandard but emphatic negative
"I don't never go"
(2) An affirmative constructed from two negatives
"A not unwelcome outcome"
WiktionaryText
Noun
- A phrase in which there are two negative words or their compounds (e.g. no, not, never, none, etc), occasionally leading to ambiguity in the meaning, but necessary in some foreign languages.
Usage notes
Often used pejoratively to characterize language use that has been acceptable in many vintages and dialects of English and other languages.