slang · noun, verb1
First use appears c. 1756, meaning "special vocabulary of tramps or thieves", origin unknown. Not believed to be connected with language or lingo. Possibly derived from a North Germanic source, then possibly related to Nordic language: Danish slænge, Icelandic and Norwegian Nynorsk slengja, Norwegian slenge, Swedish slänga (“to (carelessly) sling, throw, hurl; throw away, to dispose of; to flail”), with derivational nouns such as slæng, sleng, släng etc. Compare the compound: Danish slængenavn, Norwegian slengenavn, Norwegian Nynorsk slengenamn, Swedish slängnamn (“nickname, byname, informal name”, literally “sling-name”), and the phrases: Norwegian Nynorsk slengja kjeften, Swedish slänga käften (“to abuse verbally”, literally “to sling one's jowl”), Swedish slänga ur sig (“to say something hastily, carelessly, thoughtlessly”, literally “to throw out of oneself”), also Swedish (regional) slänga (“careless, nonchalant girl”, literally “sling + feminine suffix -a”).
slang · noun2
Compare sling.
slang · verb3
The same as sling which is also used in this sense. The vowel exhibits the lowering of /ɪ/ before /ŋ/ distinguishing for African American Vernacular English, as in thang for thing, but the word has spread with this pronunciation outside the accents that exhibit this feature.
Etymology from Wiktionary, CC BY-SA 4.0.