adj
Common
bats
bats
Bats (adj) means Informal: crazy or mentally unstable. Example: “He's gone completely bats since the divorce.”
adj
1
Informal: crazy or mentally unstable.
"He's gone completely bats since the divorce."
"You must be bats if you think I'll jump off that cliff."
"The whole plan sounds completely bats to me, but let's try it anyway."
How to use bats
Learner’s notesIn plain EnglishAn informal way of calling someone or something crazy.
When to use it
Informal/dated — you'll hear it more in older British writing than everyday modern speech.
Easily confused with
Vocabulary Flow
Build your vocabulary from words like bats.
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
Word forms
- Comparative
- more bats
- Superlative
- most bats
Fill the gap
Can you complete this real example?
He's gone completely _____ since the divorce.
Etymology
From "bat(man)" plus the hypocoristic -s ending, likely reinforced by the phrase "bats in the belfry."
Synonyms
View more →Antonyms
Related words
Rhymes for bats
See all rhymes for bats →Frequently asked questions
What does “bats” mean?
The word “bats” means informal: crazy or mentally unstable. In plain terms, an informal way of calling someone or something crazy.
How do you pronounce “bats”?
“Bats” is pronounced bats (/bæts/ in IPA).
How do you use “bats” in a sentence?
Here is “bats” used in a sentence: “He's gone completely bats since the divorce.”
What part of speech is “bats”?
“Bats” is an adjective.
Is “bats” a common word?
“Bats” is a fairly common word in modern English.
What is the difference between "bats" and "batty"?
Both are informal words meaning crazy or mentally unstable, and they are largely interchangeable. "Batty" is slightly more common as a standalone adjective, while "bats" is often used in predicate position, as in "he's gone completely bats."
Is "bats" a polite way to describe someone's mental state?
No, "bats" is informal slang and can sound dismissive or mocking, so it is best avoided in formal, medical, or professional contexts. It is typically used in casual conversation to describe eccentric or irrational behaviour rather than a genuine clinical condition.
What is the origin of using "bats" to mean crazy?
The expression is generally understood to come from the phrase "bats in the belfry," describing a mind as chaotic as bats flying around a bell tower. It remains an informal, colloquial usage rather than standard or technical language.
