A word’s denotation is its dictionary definition. A word’s connotation is the emotional baggage, so to speak, that it has acquired through popular usage. Consider words that we use to describe types of laughter: giggle, cackle, snicker, and chortle. They all name a kind of laughing, but they have really different connotations. The word giggle connotatively suggests innocence, youthfulness, and maybe even silliness. The word cackle, on the other hand, connotatively suggests age and has a distinctly witchy feeling about it, because of lots of fictional witches who cackle wildly: Disney’s Witch Hazel, the Wicked Witch of the West, and so on. The word snicker connotatively suggests a bit of mean-spiritedness, like a group of people who are laughing at someone else. Finally, the word chortle connotatively suggests a rather dignified laugh of someone of high rank who might even be British. All of these connotations accrue through usage.
Consider another group of words that has to do with being smart: intelligent, nerd, and egghead. Intelligent has a pretty positive connotation; mostly people would not mind being called intelligent. The words nerd and egghead, however, have connotations that are more negative, as though the person only possesses book smarts, as opposed to street smarts, and that being book-smart is really the only thing they have going for them.
Consider, also, words like inexpensive and cheap. Both are adjectives that describe something that doesn’t cost much money; however, inexpensive is far more positive in connotation than cheap is. If something is inexpensive, for example, it sounds like a good deal, like one is getting something for less money than is typical or expected. Cheap, however, is quite negative connotatively, as though the thing it describes is of poor quality or value.