The words complement and compliment are commonly confused in English. Once you’ve read through this lesson, your friends will compliment you on your mastery of English.
Complement is a noun and verb. It also has a matching adjective, complementary. In any case, it refers to something that completes or goes well with something.
The sauce is a nice complement to the vegetables.
The sauce complements the vegetables nicely.
The sauce is nicely complementary to the vegetables.
He has a full complement of old books.
This book will complement his collection.
I’m looking for a special shelf complementary to my book collection.
Compliment is also a noun and a verb. It indicates the offering of praise or flattery to another person, as does the adjective complimentary.
He gave me a compliment about my dress.
He complimented me on my dress.
He was very complimentary about my dress.
Thanks for the compliment
Thanks for complimenting me
Thanks for being complimentary
Complimentary can also mean free.
The champagne was complimentary.
He gave me a complimentary copy of his new book.
The Bottom Line
The word pairs complement/compliment and complementary/complimentary are pronounced identically, hence the confusion in spelling. Just remember that complement with an E means "to complete" or "to enhance," while compliment with an I means "to praise" and complimentary means "free."