There are a number of confusing, similar words in the English language, and none more so than complimentary and complementary. These two words are always being used incorrectly, and the majority of people don’t know when and how to use each instance. Contrary to popular belief, the two are not interchangeable, and are in fact used to highlight entirely different situations.
First let’s look at the word “complimentary”…
The easiest way to remember when to use this version of the word is when you say something nice about someone or something. So, you might say one of the following;
“I gave her a big compliment”.
“I complimented him on his football skills”.
“Thank you for the compliment”.
Remember: Use “compliment” for flattery and to “compliment” appearance.
Now let’s look at the word “complementary”…
The easiest way to remember when to use this version of the word is when you comment on the completion of a set or a group. So, you might say one of the following:
“The tiles really complement the floor”.
“The new software update will complement the existing system”.
“This pair of shoes will complement my dress”.
Remember: Use complement for a set, a matching pair, or an addition to a group.
But hang on…what about getting something for free?
In this instance we are dealing with a form of flattery, and therefore the word takes on the form of “complimentary”.
So you would say:
“A complimentary coffee on arrival at the hotel”.
“Complimentary WIFI with the apartment”.
Complementary vs Complimentary In Summary
Okay. So let’s summarise all this information and use both words across three instances in one sentence:
“The waitress gave me a complimentary coffee so I complimented her on her efficient service. But to be honest, the restaurant décor didn’t complement the high level service in the slightest.”
If you are still unsure, another trick you can use is to ask yourself whether or not the compliment/complement is talking to its subject. For example, my shoes aren’t talking to my suit, so therefore the shoes complement my suit. Yet I am paying my mum a compliment when I say to her that she looks very well.