As homonyms, these two words are often confused in writing. It is rare that people use complement when they actually mean compliment, it is typically the other way around. There is, however, a simple way to resolve the issue and break the habit of using the wrong spelling. First we define the two.

Compliment: an expression of praise or admiration. He complimented me on my dress, saying it brought out the color of my eyes.

Complement: a quantity or amount that completes anything. The horned helmet complemented the warrior's armor.

When I was a child I learned the difference between the spelling of principle and principal by simple association. I was taught that principal applies to a person (or position) by looking at the word pal found at the end. A principle is not a person, thus cannot be a pal. A principal is a person, and [he] is your pal. Similarly, association can be made when considering the homonyms compliment and complement.

The easiest way to remember the difference is by considering the root. The root of complement is complete. Therefore, complement is defined by completion, adding a piece to a whole. If you can remember that then you should never confuse the two again.

This also applies to the adverbial usage (complimentary / complementary). Consider that complimentary refers to something favorable. The latter complementary is not as often used.

  • My mother made some very complimentary remarks about my shoes.