It’s fascinating to me that in everyday English, the same word can have two meanings that are completely opposite. Even more fascinating is that, generally, people know exactly which meaning you intend simply from the context. I mean, they don’t have to think about it or wonder or ask for clarification; somehow it’s just obvious.
For example, if your boss tells you she is going to garnish your wages, you don’t stop to ask if she is going to add something to them, like a sprig of parsley. No, you immediately understand that she is going to subtract something from your regular paycheck.
Cleave is another such word. When a husband and wife cleave to each other, they stay together. When a butcher cleaves a pork roast, he chops it apart.
Even the little preposition with can have opposite meanings! If you say, “I fought with my brother,” do you mean that you fought against him or alongside him?
Words that can have opposite meanings are called contronyms. Just for fun, I’m listing a few here:
1. Left (departed, or remaining)
All the editors left the room, so only the writer was left.
2. Dust (to remove fine particles, or to add them)
While she dusted her antique typewriter, he dusted the cupcakes with powdered sugar.
3. Fast (to keep from moving, or to move quickly)
I held the paper fast, so it wouldn’t move while I was writing so fast.
4. Bill (an invoice, or a payment)
When you receive a bill from LifeLines, you can pay it with a check, a credit card, or a straight-up hundred-dollar bill.
5. Bolt (to secure, or to flee)
Her boots were bolted to the floor, but she slipped out of them and bolted for the door.
6. Strike (to hit, or to miss)
When Casey’s bat failed to strike the ball, the ump called, “Strike three!”
7. Variety (one type, or many types)
There is such a variety of vegetables in my garden, I can’t choose which variety of tomatoes I like best!
8. Custom (a common practice, or personalized treatment)
It is my custom to write a custom response to each comment on the LifeLines blog.
You can find many more examples of contronyms at Mental Floss, Daily Writing Tips, and other sources around the interweb. In many cases, you’ll find that you are so familiar with both meanings that you didn’t even realize they were opposites until you had to stop and think about it!