Use conscience, a noun (a naming word), for your inner sense of right and wrong. Use conscious, an adjective (a describing word), when someone is awake, aware of something, or acting on purpose.
The difference between conscience and conscious shows up in the endings. The -ence ending often marks a noun, as in patience. The -ous ending often marks an adjective, as in nervous.
- She couldn’t, in good conscience, sign off on numbers she hadn’t checked.
- The nurse checked whether the cyclist was conscious before moving him.
What Your Conscience Tells You, and the Phrases Built on it
Your conscience is the part of your mind that judges your own actions. The word can also mean a guilty feeling, or the act of standing by what you believe.
It shows up most often in a few fixed phrases:
- in good conscience or in all conscience: honestly, without going against your own sense of fairness
- on your conscience: making you feel guilty
- freedom of conscience: the right to act on what you believe is right
- a matter of conscience: a choice each person makes for themselves
The board treated the vote as a matter of conscience, not party loyalty. Afterward, the referee’s call weighed on his conscience for weeks.
The plural is consciences, though you’ll rarely need it: “Several members followed their consciences and voted no.”
Four Jobs Conscious Does in a Sentence
| Meaning | Example |
| Awake | My grandmother stayed conscious and joking through her cataract procedure. |
| Aware of something | I’m conscious that this email is long, so the key dates are at the top. |
| Deliberate | The coach made a conscious choice to rest his star player before the playoffs. |
| Caring about something | Budget-conscious students often rent textbooks instead of buying them. |
In the “aware” sense, conscious usually follows a verb rather than sitting before a noun: “Tour guides are conscious of the noise rules near the cathedral.” The matching noun is consciousness, as in “He lost consciousness.”
Where Dictionaries and Experts Disagree About Conscious
On the basics, every source agrees. On the points below, respected references give different answers, and editors run into these cases.
| Question | One answer | A different answer |
| Can conscious be a noun? | Yes, in psychology (“the conscious”), says Merriam-Webster, dating it to 1919. American Heritage and Collins agree. | No. Paul Brians says conscious alone can’t mean consciousness. |
| Is unconscious the opposite of “conscious of”? | Yes, says Oxford Learner’s. | Not for the “keenly aware of” sense, says LanguageTool. |
| When did conscious enter English? | 1573, according to the OED, as reported on the OUP blog. | Around 1600, say Merriam-Webster’s dictionary and Etymonline. |
| What did it first mean? | Aware of your own wrongdoing (OED). | Knowing, or being in on a secret (Etymonline). |
| Is “conscious sedation” still the right medical term? | No. It’s been dropped from anesthesiology standards (details in the next section). | Many dentists still use it for moderate sedation. |
| When did “conscious uncoupling” start? | 2006, in a Massey University paper found by Word Spy. | 2009, coined by therapist Katherine Woodward Thomas, per Wikipedia. Dictionary.com dates it to 2010–15. |
| Is subconscious a proper psychology term? | Dictionary.com treats it as an ordinary noun. | Brians says Freudian psychology doesn’t use it, though Jungian psychology does. |
Using Conscious as a Noun
The noun use is real, but it lives in psychology writing. “The conscious and the unconscious” reads fine in an article about Freud. In everyday writing, consciousness is the safe choice, and no reader will object to it.
Picking an Opposite for “Conscious of”
For being awake, the opposite is clearly unconscious. For “aware of,” the sources split, so reach for unaware of. “She was unaware of the deadline” can’t be misread. “She was unconscious of the deadline” sounds like she fainted.
Dating the Word
Merriam-Webster’s own usage article places conscious in the 16th century, while its dictionary entry says circa 1600. If you need a date, the OED’s 1573 is the earliest evidence, and you can say so plainly.
How Doctors, Lawyers, and the Military Use these Words
Medicine. The American Society of Anesthesiologists no longer includes “conscious sedation” in its standards. The preferred term is moderate sedation, a drug-induced state where the patient still responds to a voice or a light touch. In 2005, American Family Physician advised dropping the older term. The dental clinic now says “moderate sedation” in its consent forms.
Doctors also use minimally conscious state when making treatment decisions for severely brain-injured patients.
Law and health policy. Here, conscience often sits before another noun, as in “conscience laws” or “conscience protections.” The U.S. Department of Health and Human Services enforces federal conscience protection laws. One group of them, the Church Amendments from the 1970s, lets providers refuse to take part in abortion or sterilization.
The military. A conscientious objector refuses to fight because of conscience. The Selective Service says these beliefs can be moral or ethical rather than religious. They can’t rest on politics, convenience, or self-interest. A conscientious objector may be assigned alternative service rather than combat.
Psychology. Merriam-Webster gives a psychology sense of conscience: the part of the superego that sends commands to the ego. This is also where “the conscious” works as a noun.
Self-Conscience, Cost-Conscience, and Other Slips That Reach Print
These mix-ups get past professional editors too. Merriam-Webster collected examples from Travel + Leisure, Forbes, and Popular Mechanics.
| Incorrect | Correct |
| a guilty conscious | a guilty conscience |
| be conscience of your body language | be conscious of your body language |
| cost-conscience homeowners | cost-conscious homeowners |
| self-conscience | self-conscious |
He grew self-conscious about his accent during the job interview.
A few related words cause their own trouble:
- Unconscience isn’t a word. You probably mean the unconscious or conscience.
- Conscientious means careful and thorough, guided by your conscience: “The developer was conscious of the deadline, but she stayed conscientious about security testing.”
- Unconscionable means beyond what’s reasonable or fair. It survives from an old word, conscionable, which fell out of use in the early 1700s.
For hyphens, Oxford’s examples show health-conscious with a hyphen but environmentally conscious without one. When the first word ends in -ly, leave the hyphen out.
Why Two Words Grew from One Latin Root
Both words come from Latin com- (“with”) and scire (“to know”). The Latin verb conscire meant to be aware of guilt, so moral awareness was there from the start.
Conscience reached English in the 13th century. Merriam-Webster still lists “consciousness” as an old, archaic meaning of conscience, which shows how long the two ideas shared one word. Before the Latin word took over, Old English sometimes used its own word, inwit.
Conscious took on its meanings slowly. The OED dates the “deliberate” sense to 1726. Etymonline dates the “awake” sense to 1837.
If you learned French first, watch this pair closely. The French word conscience covers both meanings: perdre conscience means “to lose consciousness.” English splits that one word into two.
Saying Conscience and Conscious Aloud
Conscience sounds like KON-shuhns. Conscious sounds like KON-shuhs. The only difference is the “n” sound near the end.
Merriam-Webster also lists a variant of conscience that sounds closer to KON-chuhns, with a “t” sound slipping in. Both pronunciations are standard.
Can someone be conscious without a conscience?
Yes. The two words name different things. A scammer can be wide awake and aware of every lie while feeling no guilt at all.
Is awareness the same as consciousness?
The two overlap, but only consciousness covers being awake. You lose consciousness, not awareness, when you faint. American Heritage notes a finer point: conscious leans toward what you feel or sense directly, and aware toward what you’ve learned from information.
To test a sentence, try swapping in aware, awake, or deliberate. If one fits, write conscious. If you need a noun about right and wrong, write conscience. In medical copy, use “moderate sedation,” since the profession has already retired “conscious sedation.”
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I’m Hazel, and I studied BSC English at GCUF. I focus on explaining word meanings in simple, clear language that anyone can understand. My goal is helping readers grasp everyday English, confusing terms, and slang used in real conversations and social media. I believe language learning works best when definitions connect to actual life situations. Through careful research and straightforward explanations, I make vocabulary accessible for students, learners, and anyone curious about how English really works in daily use.