Connotation and Denotation
Denotation is the dictionary definition of a term. It is the literal meaning of a word, what a term means.
Connotation is the emotions, thoughts, images, and associations attached to a word. It is what a term implies. Terms can have positive, negative, or even neutral connotations. It all depends on the context, how and where the word is used.
A set of terms could have the same denotation (definitions), but make different impressions on readers because they have different connotations, or they are used in a certain way to imply different meanings.
Let’s look at two pairs of terms that have very similar denotations, but different connotations.
Example #1: berserk and irrational
Both terms denote unreasonable and illogical behavior
Berserk connotes behavior that is completely out of control, to the point of being reckless. It is a more extreme term
Irrational connotes behavior that is simply absurd or senseless; it implies a lack of logic rather than a lack of control.
Example #2: to finish and to terminate
Again, both terms denote bringing something to an end
“To finish” can have positive connotations: a sense of completion and accomplishment (finishing school, crossing the finish line); it can also have neutral connotations (I finished folding the laundry); and it can sometimes have negative connotations: a sense of an eternal end (You’re finished in this town! You’ll never work here again!)
“To terminate” really only has negative connotations: termination implies an eternal end, but does not imply completion or accomplishment. No one ever races to cross the “termination line.”
Again, we can see that one term is much more extreme than the other, even though they are very similar.
Source: Definitions from Merriam-Webster's Collegiate Dictionary