It's interesting how some of these increase until you see them everywhere. I wonder whether there's a tipping point beyond which the mis-use goes viral.
The one I'm referring to this time is compliments vs. complements.
Compliments are postiive statements or praise ("In her journal she wrote all of the compliments she received") or the act of making such statements ("He compliments every woman he meets"). The adjective form is complimentary ("Everything he said about you was complimentary").
Complimentary also can refer to something that's free ("The first drink is complimentary"). In that context sometimes people will say that the free thing is "compliments of the hotel" (or whoever is doing the giving).
Complements is a verb, meaning that the subject in question is a good addition to or match with something else. ("That bag complements her outfit").
The adjective complementary refers to something that matches, supplements, or completes. For instance, "The bag and the dress are complementary." That's clear enough when written, but if the store clerk said that you might think they're free.
As a noun, complement means a set of something, like the full set of officers and crew on a ship, or a set of services or items ("We offer a complement of blood tests").
You'll find many examples of mixing these up. What triggered this rant was a photo caption on the Huffington Post site: "A Venetian mask compliments this stroll through the Italian city's cobbled streets."
On the Ask site, someone posed the question, "What is Complement?" and the only answer on that page is, "A complement is something someone says to you regarding your work performance or your personal appearance. Wow, your hair looks great today or great job on finisihing that project early."
If you find it hard to remember the difference, the phrase "I like to get compliments" is useful--the "I" reminds you to spell the word with an i.
(If you'd like friendly guidance for writing your novel, you'll find it in my book, "Your Creative Writing Masterclass." It's published by Nicholas Brealey and available from Amazon or your other favorite book seller.)