Quick answer: Common describes something found or happening frequently — it is about how widespread or frequent something is. Ordinary means standard, not special or remarkable — it is about the quality or status of something. A cold is common (happens often); Monday is an ordinary day (nothing special about it). For a fuller definition, see the Cambridge Dictionary entry for ‘common’.
Understanding Common
Common primarily describes things that occur frequently, are widely found, or are shared by many people. A common cold is one that many people get; a common mistake is one that many people make; common ground is something shared by many. Common also has specific uses: common sense, the common good, common law, and in British English, a common (an area of public land). When applied to people in an informal British context, common can be an insult suggesting a lack of refinement — this is a sensitive usage. The word can also mean shared: “we have a common interest.” The noun form includes commonness and the adverb is commonly.
Colds and flu are especially common in winter.
It is common knowledge that the project was delayed.
The two companies share a common goal of reducing emissions.
Common sense tells you not to leave valuables in plain sight.
Understanding Ordinary
Ordinary means normal, standard, or not special. It describes something that fits the expected pattern without standing out as remarkable or exceptional. An ordinary day is one with nothing noteworthy; an ordinary person is someone without fame or unusual qualities. The word is used positively when celebrating the ordinary — as in stories about ordinary heroes — and slightly negatively when contrasting with the exceptional. The opposite is extraordinary, which literally means “outside the ordinary.” The adverb ordinarily means “in the normal course of events.” Ordinary often appears in formal language: “in the ordinary course of business.”
It was just an ordinary Tuesday — nothing unusual happened.
She is an ordinary person who found herself in extraordinary circumstances.
Ordinarily, the meeting ends by noon.
The food was good, though nothing out of the ordinary.
Key Differences at a Glance
| Use case | Common | Ordinary |
|---|---|---|
| Main meaning | Frequent / widespread | Standard / not special |
| Applied to people (British English) | Can be insulting (lack of refinement) | Neutral (not famous or exceptional) |
| Fixed phrases | common sense, common ground, common law | out of the ordinary, ordinary person |
| Opposite | rare / uncommon | extraordinary / remarkable |
| Adverb form | commonly | ordinarily |
Common Mistakes
✗ It was a very common day at the office. (unusual)
✓ It was a very ordinary day at the office. (nothing special happened)
✗ She has a lot of ordinary sense.
✓ She has a lot of common sense.
✗ She thought his accent was very common. (may be taken as an insult in British English)
✓ Use ordinary or a neutral descriptor if no insult is intended.
Practice: Which Is Correct?
Four questions — choose the best word.
1. “Headaches are a ___ side effect of this medication.”
2. “Nothing out of the ___ happened during the shift.”
3. “They found ___ ground and reached a compromise.”
4. “She led a very ___ life in a small town.”
Frequently Asked Questions
What is the difference between common and ordinary?
Common describes something found or happening frequently. Ordinary means standard, usual, not special or remarkable. The first focuses on frequency; the second on quality or status.
Can common and ordinary be used interchangeably?
Sometimes, but they emphasise different things. Common = widespread; ordinary = unremarkable. “A common cold” means it occurs frequently. “An ordinary day” means it was nothing special.
Can common have a negative connotation?
Yes. In British English, calling a person “common” can be an insult meaning they lack refinement or social grace. In this use, it carries a strong class connotation.
What is the opposite of ordinary?
The opposite of ordinary is extraordinary, unusual, remarkable, or special. The opposite of common (in the sense of frequency) is rare or uncommon.
What does “common knowledge” mean?
“Common knowledge” means something that most people know — it is widely known and shared. You would not say “ordinary knowledge” in this context.
What does “out of the ordinary” mean?
“Out of the ordinary” means unusual, remarkable, or different from what is expected. You would not say “out of the common” in standard modern English.
Is ordinary more negative than common?
Ordinary is mildly negative when applied to things (it implies lack of distinction) but neutral when describing expectations. Common can be strongly negative when applied to people in British English.
What is a “common room”?
A common room is a shared space in a school, college, or workplace that everyone can use. Here “common” means shared by all, not “frequent” or “ordinary”.
Can ordinary mean “in the usual way”?
Yes, especially in the phrase “in the ordinary course of events” meaning in the usual or expected way. This is a formal or legal use.
What is the adverb form of ordinary?
The adverb form is ordinarily: “Ordinarily, the office closes at five.” There is no standard adverb form of common in this adjective sense (not “commonnly”; the adverb is commonly).