sol·e·cism / ˈsäləˌsizəm; ˈsō-/ • n. a grammatical mistake in speech or writing. ∎  a breach of good manners; a piece of incorrect behavior.DERIVATIVES: sol·e·cis·tic / ˌsäləˈsistik; ˌsō-/ adj.

SOLECISM, formerly soloecism. A traditional term for the violation of good grammar and manners, and any instance of this, such as saying I didn't do nothin' instead of I didn't do anything (especially if done by someone who ‘ought to know better’). The term has often been used in tandem with BARBARISM, the perceived ABUSE of words.

solecism violation of good grammar or good manners; impropriety. XVI. — F. solécisme or L. solœcismus — Gr. soloikismós, f. sóloikos using incorrect syntax, etc., said by ancient writers to refer to the corruption of the Attic dialect by Athenian colonists at Soloi in Cilicia; see -ISM
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solecism a grammatical mistake in speech or writing; a breach of good manners, or piece of incorrect behaviour. The word is recorded from the mid 16th century, and comes ultimately from Greek soloikismos, from soloikos ‘speaking incorrectly’.