noun Uncommon

lunatic

LOO-nuh-tihk

Quiz me More like this

Lunatic (noun) means a person regarded as insane or wildly irrational (now considered old-fashioned and offensive as a clinical term). Example: “The old asylum was once, insensitively, referred to as a home for lunatics.”

noun

A person regarded as insane or wildly irrational (now considered old-fashioned and offensive as a clinical term).

"The old asylum was once, insensitively, referred to as a home for lunatics."

adj

Crazy, reckless, or completely irrational.

"Only a lunatic would try to cross that motorway on foot."

"He came up with some lunatic scheme to double his savings overnight."

How to use lunatic

Learner’s notes

In plain EnglishSomeone or something completely crazy or irrational.

When to use it

As a label for a person with mental illness, this word is now considered offensive and dated; it survives mainly in the looser sense of "reckless" or "absurd," as in "lunatic idea."

Common pairings

a lunatic idea lunatic asylum (dated) lunatic fringe

Vocabulary Flow

Build your vocabulary from words like lunatic.

Vocabulary Flow serves the next word, and the next — meaning, pronunciation and an example each time. Practice at your level, or learn English in your own language.

Start vocabulary practice

C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

Word forms

Plural: lunatics
Comparative: more lunatic
Superlative: most lunatic

Test yourself on “lunatic” A quick quiz — meaning, synonyms & usage →

Fill the gap

Can you complete this real example?

The old asylum was once, insensitively, referred to as a home for _____.

Etymology

From Old French lunatique, from Late Latin lunaticus ("moonstruck"), from Latin luna ("moon") — reflecting the old superstition that changes in the moon triggered fits of madness.

Origin: Late Latin

Synonyms

View more →

maniac swashbuckler madcap daredevil hothead moonstruck crazed insane mad demented maniacal psychotic

Antonyms

sane

Related words

crazy fan mad hero angry fantastic reasonable crack

Rhymes for lunatic

static somatic aquatic fanatic hepatic erratic aromatic ecstatic operatic dramatic climatic emphatic

See all rhymes for lunatic →

Frequently asked questions

What does “lunatic” mean?

The word “lunatic” means a person regarded as insane or wildly irrational (now considered old-fashioned and offensive as a clinical term). In plain terms, someone or something completely crazy or irrational.

How do you pronounce “lunatic”?

“Lunatic” is pronounced LOO-nuh-tihk (/ˈluːnətɪk/ in IPA).

How do you use “lunatic” in a sentence?

Here is “lunatic” used in a sentence: “The old asylum was once, insensitively, referred to as a home for lunatics.”

What is another word for “lunatic”?

Words with a similar meaning to “lunatic” include crazed, insane, mad, demented, maniacal and psychotic.

What part of speech is “lunatic”?

Depending on how it is used, “lunatic” can be a noun and an adjective.

Where does the word “lunatic” come from?

The word “lunatic” comes from Late Latin. From Old French lunatique, from Late Latin lunaticus ("moonstruck"), from Latin luna ("moon") — reflecting the old superstition that changes in the moon triggered fits of madness.

Is “lunatic” a common word?

“Lunatic” is an uncommon word in modern English.

How many meanings does “lunatic” have?

“Lunatic” has 2 distinct senses listed in this dictionary. The most common is: a person regarded as insane or wildly irrational (now considered old-fashioned and offensive as a clinical term).

Featured in

Vocabulary lists that include lunatic:

Words that end with C

People also searched

crazy fan mad hero angry fantastic reasonable crack