Are peanuts addicting or additive?  Both are correct, but there is actually a slight difference in nuance.  "Addictive" is clearly an adjective.  "Addict" can be either a noun or a verb depending on the accent.  ADD-ict, is a noun, meaning a person who is addicted to something, while "add-ICT" is a verb meaning to cause someone to become an addict: "I addict people to cocaine."  So, what is "addicting"?  If we can put the word "very" in front of "addicting," it must be considered an adjective, and we can.  Thus, addicting, like addictive is an adjective, but built from the verb add-ICT.  Since addicting is build from a verb, it has a verb quality, whereas "addictive" does not.  So, if we say peanuts are addictive, we are talking solely of the peanuts, but if we say peanuts are addicting, we are talking about how the peanuts are affecting us.  In fact, any present participle adjective describes something as to its affect on something else: The movie is boring, the water is soothing, the music is deafening, etc.  So, it is probably more correct to use "addicting" in situations where you are talking about how something affects you personally (or giving a warning to someone else), while it would be more proper to use "addictive" is situations where you are trying to be objective, such as in a medical report, e.g., "The study proved that marijuana is addictive."       

Return to list of errors