Low, vulgar, unauthorized language; a popular but unauthorized word, phrase, or mode of expression; also, the jargon of some particular calling or class in society; low popular cant; as, the slang of the theater, of college, of sailors, etc.
To address with slang or ribaldry; to insult with vulgar language.
My mother wouldn't allow me to speak slang when I was growing up. But when I got outside, around my friends, it was 'Yo' and 'That's the joint' and 'Yo, what's up?' So I had my game for my friends and my game for my mom. Queen Latifah
'Chamalkay' is an old Guyanese slang word. It means a 'young mischievous girl.' It's not derogatory, but it isn't over complimentary, either. It was probably a word I just Googled one day, and the song kind of played into the feel of that. Dev Hynes
The sea speaks a language polite people never repeat. It is a colossal scavenger slang and has no respect. Carl Sandburg
It is too late to be studying Hebrew; it is more important to understand even the slang of today. Henry David Thoreau