Words get confused for one of three reasons: they sound alike (stationary/stationery), they look alike (discreet/discrete), or their meanings overlap just enough to blur (imply/infer). The cure is almost always a single, memorable rule. Below are quick, reliable rules for 15 pairs that catch out even careful writers — each with a correct and an incorrect example so you can see the difference at a glance.
A complement completes something; a compliment is praise. ✓ The wine is a perfect complement to the meal. ✓ She complimented his cooking. ✗ The wine is a perfect compliment to the meal. Watch the -ary forms too: complimentary means free or flattering (a compliment costs nothing), while complementary means matching or completing. Memory trick: complEment complEtes.
Stationary (with an a) means standing still; stationery (with an e) means writing paper. ✓ The car stayed stationary at the lights. ✓ headed notepaper and other stationery. ✗ We ordered new office stationary. Memory trick: stationery goes with envelopes; stationary goes with at rest.
Principal is the main person or thing (or a sum of money); a principle is a rule or belief. ✓ the school principal, the principal reason, pay down the principal. ✓ a matter of principle, the principles of physics. ✗ She is the principle violinist. Memory trick: the principal is your pal; a principle is a rule.
Discreet means careful or tactful; discrete means separate or distinct. ✓ a discreet inquiry. ✓ three discrete categories. ✗ The data falls into three discreet groups. Memory trick: in discrete, the t keeps the two e's apart — discrete things stay separate.
Use fewer for things you can count; use less for amounts you can't. ✓ fewer mistakes, less sugar. ✗ less mistakes. The big exception: measurements, money and time take less even though they look countable — less than 20 miles, less than $50, less than three weeks — because you're treating them as one quantity. And the “10 items or less” sign isn't illiterate: the strict rule is barely 250 years old, and less with countables is far older. Still, editors expect the distinction, so keep it in formal writing.
Lay takes an object (you lay something down); lie doesn't (you lie down yourself). ✓ Lay the book on the table. ✓ I need to lie down. ✗ I'm going to lay down. The trap is the past tense: the past of lie is lay (Yesterday I lay on the sofa), while the past of lay is laid (She laid it down). Telling a falsehood is a third verb entirely: lie, lied, lied.
A speaker implies (hints); a listener infers (concludes). ✓ He implied I was late. ✓ From her tone, I inferred she was annoyed. ✗ Are you inferring I'm a liar? — you mean implying. Memory trick: the speaker Implies; you Infer.
Farther is for physical distance; further is for figurative distance, degree or “additional.” ✓ two miles farther down the road. ✓ let's discuss this further, no further questions. ✗ farther study is needed (not distance, so use further). This is a soft rule, though: in British English further comfortably does both jobs, and it's never wrong for distance either. When unsure, further is the safe pick; save farther for literal miles.
Elicit is a verb meaning to draw out; illicit is an adjective meaning illegal. ✓ The question elicited a laugh. ✓ an illicit affair. ✗ The police seized elicit substances. Memory trick: illicit is illegal — both start ill-.
Disinterested means impartial; uninterested means bored or indifferent. ✓ a disinterested referee. ✓ uninterested in the lecture. ✗ He seemed disinterested in his dinner. Historically the two were tangled — disinterested once meant “not interested” — but modern usage keeps them apart, and the split is worth protecting: a judge should be disinterested (no stake) yet never uninterested (they must pay attention).
You pore over a document (study it closely); you pour a liquid. ✓ She pored over the contract. ✓ Pour the milk. ✗ He poured over the map for hours — unless he spilled his coffee on it.
Pique means to arouse (interest); a peak is a summit; a peek is a quick look. ✓ The trailer piqued my curiosity. ✓ the mountain's peak, peak performance. ✓ a quick peek behind the curtain. ✗ The trailer peaked my curiosity. “Peaked my interest” is one of the most common slips in English — it's always piqued.
Flout means to defy or disregard; flaunt means to show off. ✓ They flout the rules. ✓ She flaunts her wealth. ✗ They flaunt the rules — a very common mix-up that says the opposite of what's meant. Memory trick: “if you've got it, flaunt it” (display); flout rhymes with out — you throw the rules out.
e.g. means “for example”; i.e. means “that is” or “in other words.” ✓ citrus fruits, e.g. lemons and limes. ✓ the capital, i.e. London. ✗ the capital, e.g. London — there's only one, so it's a restatement (i.e.). Memory trick: e.g. = example given. US style adds a comma after each (e.g.,); UK style usually doesn't.
You assure a person, ensure a thing happens, and insure against financial loss. ✓ I assure you it's fine. ✓ Ensure the door is locked. ✓ insure the car. ✗ Ensure you it's fine. British English blurs ensure and insure a little, and — a genuine quirk — UK policies say life assurance rather than life insurance, because death is a certainty.
A few of these deserve honesty. The fewer/less distinction and the disinterested/uninterested split are useful conventions, not ancient laws — both have been bent by good writers for centuries, and neither is a grammatical crime. The farther/further divide is softer still, especially in Britain. Follow them anyway in careful writing: not because breaking them is “wrong,” but because observing them signals precision and never confuses a reader. That is the whole point of a usage rule.
“e.g.” stands for the Latin exempli gratia, “for example,” and introduces one or more samples from a larger set: “citrus fruits, e.g. lemons.” “i.e.” stands for id est, “that is,” and restates or clarifies exactly what you mean: “the capital, i.e. London.” If you could swap in “for example,” use e.g.; if “in other words” fits, use i.e.
Use “fewer” for things you can count individually — fewer cars, fewer mistakes — and “less” for uncountable amounts, such as less traffic or less time. The exception trips people up: measurements, money and periods of time take “less” even though they seem countable, as in “less than 20 miles” or “less than $50,” because you are treating them as a single quantity.
You “pore over” a book, map or document — the verb “pore” means to study or read something with close attention. “Pour” refers only to making a liquid flow, so “pour over the report” literally means to spill something on it. An easy reminder: you pore over pages, but you pour a drink.
The correct phrase is “piqued my interest.” To “pique” means to arouse or stimulate, so something that piques your interest sparks your curiosity. “Peak” means a summit or highest point, and “peek” means a quick look — neither fits here. “Peaked my interest” is one of English's most common spelling slips.
You “assure” a person by removing their doubt (“I assure you it's ready”); you “ensure” something by making it certain to happen (“ensure the door is locked”); and you “insure” property or a life by taking out financial cover (“insure the car”). In British English, “life assurance” is the standard term for life insurance.
