Meaning of the word "bosom friend" in English

What does "bosom friend" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

bosom friend

US /ˈbʊzəm frɛnd/
UK /ˈbʊzəm frɛnd/

Phrase

a very close and intimate friend

Example:
She shared all her secrets with her bosom friend.
They have been bosom friends since childhood.