Sisters–in-law or Sister-in-laws
Whenever you’re pluralising a compound noun, the plural should go to the noun of which there’s more. Since in this case there are more sisters and not more laws, it’s “sisters-in-law,” not “sister-in-laws.” The same rule applies to “surgeons-general” and “attorneys-general.”
He did good or He did well
Nope. He did well. Similarly, when someone asks how you’re doing, the answer should always be “I’m doing well,” not, “I’m doing good.” That is, if you are actually doing well. If you’re doing catastrophically poorly, by all means say that.
Unphased or Unfazed
This word doesn’t actually exist. If you want to say someone was completely unaffected by something, it’s “unfazed.” Used in a sentence: “She remained unfazed by her daughter’s tantrum, calmly carrying her through the mall.”
Waiting with baited breath or Waiting with bated breath
Bait is what you use to hook fish […] What you want to say is “bated breath,” which comes from the word “abate,” meaning to reduce or diminish. Thus, if you’re waiting with bated breath, you’re so nervous/excited you can hardly breathe.
Palm off or Pawn off
You actually want to say “palm off,” which comes from cards. When a dealer sneakily deals a low card on purpose, it’s known as palming it off. So don’t pawn off that awful project in January — palm it off.
Slight of hand or Sleight of hand
Another one about deception, this should actually be “sleight of hand.” The word “sleight” shares its origin with “sly,” and means “the use of dexterity or cunning, especially so as to deceive.” Used in a sentence: “The magician tricked us with his sleight of hand.”
Whet your appetite or Wet your appetite
This one comes from the concept of a whetstone, which is used to sharpen a knife. The idea is that you’re sharpening your hunger, so the correct phrase is to “whet your appetite.”
Take a different tack or Take a different tact
Anyone who has gone sailing will know this one. When you change direction on a sailboat, you either tack or gybe the sails (tacking is safer and more common). The correct use of this expression is thus to “take a different tack,” meaning to shift directions.
Pour over or Pore over
Ever walked in to see your boss pouring over the latest sales numbers? No, because the correct word in that sentence is “pore,” not “pour.” Studiously going over a book or other written material is “poring over” something.
Mute point or Moot point?
It might seem like “mute” is the right word here, given that it means not being able to speak. But no – it’s actually “moot point.” This comes from “moot courts,” places where law students argued hypothetical cases. Since the outcomes were essentially unimportant (they didn’t affect real laws), they were “moot.” Used in a sentence: “As an investigator, whether or not you like your clients is a moot point.”
Toe the line or Tow the Line
This is an expression that essentially means to be a follower – to go along with the policies of a particular group. However, the correct usage is “toe the line,” which comes from the military practice of putting your feet precisely on a line for inspection. Used in a sentence: “That politician hardly has an original thought; he’s just toeing the party line.”
Peak/peek one’s curiosity or Piques one’s curiosity
If something piques your curiosity, it means it stimulates you — you want to know more. It can’t “peak” or “peek” your curiosity, because it can’t summit or get a glimpse of your curiosity. If your curiosity is piqued as to what pique actually means, it comes from the French word piquer, which means to prick or nick something.
On accident or by accident
Ah, the prickly prescriptions of prepositions. This is just one to memorize: it’s always “by accident.” You can remember it like signing your name: “I wrote this entire essay by accident. – By Sarah Jones.”
inc.com/melanie-curtin/13-common-expressions-youre-probably-saying-wrong.