Let us remember that connotation refers to the words, ideas and images that come to our mind when we look at a particular word. It is of course a key skill of authors and the kind of words they select and use deliberately to produce and create a particular impression or idea in our minds. One of the biggest examples of connotation in this novel is of course with the words "fire" and "burn." We automatically think of fire as being something destructive, cleansing and dangerous. Yet also the word "burn" has connotations of cleansing and purification.
We can see from the very first lines of this book how these connotations are linked to the theme when the narrator describes the "special pleasure" that Montag takes in seeing "things eaten, to see things blackened and changed." Fire has the ability to transform one thing into something completely different and to "bring down the tatters and charcoal ruins of history." Through this connotation, the strength of fire is something that is established.