We found 4 dictionaries that define the word have bats in one's belfry:

General (3 matching dictionaries)

1. have bats in one's belfry, have bats in one's belfry: Collins English Dictionary
2. have bats in one's belfry: Wiktionary
3. have bats in one's belfry, have bats in ones belfry: Dictionary.com

Slang (1 matching dictionary)

4. Have bats in ones belfry: Urban Dictionary

Definitions from Wiktionary (have bats in one's belfry) ▸ verb:  (idiomatic, intransitive) To be crazy or eccentric. ▸ Words similar to have bats in one's belfry ▸ Usage examples for have bats in one's belfry ▸ Idioms related to have bats in one's belfry ▸ Wikipedia articles (New!) ▸ Words that often appear near have bats in one's belfry ▸ Rhymes of have bats in one's belfry ▸ Invented words related to have bats in one's belfry