We found 4 dictionaries that define the word beat one's brains out:

General (4 matching dictionaries)

1. beat one's brains out: Merriam-Webster
2. beat one's brains out: Wiktionary
3. beat one's brains out, beat ones brains out: Dictionary.com
4. beat one's brains out: ESL Idiom Page

Definitions from Wiktionary (beat one's brains out) ▸ verb:  (informal) to think very hard about. ▸ Words similar to beat one's brains out ▸ Usage examples for beat one's brains out ▸ Idioms related to beat one's brains out ▸ Wikipedia articles (New!) ▸ Words that often appear near beat one's brains out ▸ Rhymes of beat one's brains out ▸ Invented words related to beat one's brains out