Does anyone know if ever there was usage akin to slang in the ancient root languages? (And no, I am not referring to the 'spucatum tauri' kind!)

The thought came to me from the word, 'concoct'. Informally, we commonly say, 'These are cooked up facts'. Concoct could easily replace ‘cooked up’ in that sentence. I now find that concoct has a Latin root, (?Concoquere), which literally means cooked together. It seems interesting that there are proper, dictionary-ratified words, with roots that literally translate into current day slang. Almost as if, some words that might have once been in informal usage (slang even), gradually converted over the years, into more respectable dignified forms, only to revert all over again to their former selves.

Is there a name for words like this?

Can we think of some more such words?

(My apologies, for inflicting such a hideously uncreative title on all of you)

Edit: First, she creates a terrible title; then, she discovers a typo in a neologism and edits it.