There was a great book which I read and own "The Story of English: Revised Edition" By William Cran, Robert MacNeil, Robert McCrum made into a great PBS mini-series - FYI
From the most recent issue of the New York review of books: “Galvani’s name entered the English language as early as 1802, through words such as galvanize ‘to stimulate by means of a galvanic current’. But to galvanize quickly came to have a far broader meaning. During the American civil war, for instance, captured confederate soldiers who accepted freedom on the condition that they swear an oath of allegiance to the United States and enlist in federal military service were called “galvanized Yankees”, implying that they were jolted into action and somewhat insincere.”
"In American popular culture in the 1960s, “bad" came to mean “very good.""
That usage persisted into the 1980s, as per Michael Jackson's hit record and album by that name.
There was a great book which I read and own "The Story of English: Revised Edition" By William Cran, Robert MacNeil, Robert McCrum made into a great PBS mini-series - FYI
https://www.youtube.com/playlist?list=PLh06URz4IJQ4aI0A-xjXOtx2OnApu2SNn
From the most recent issue of the New York review of books: “Galvani’s name entered the English language as early as 1802, through words such as galvanize ‘to stimulate by means of a galvanic current’. But to galvanize quickly came to have a far broader meaning. During the American civil war, for instance, captured confederate soldiers who accepted freedom on the condition that they swear an oath of allegiance to the United States and enlist in federal military service were called “galvanized Yankees”, implying that they were jolted into action and somewhat insincere.”