thick and thin

Translations
в горе и в радости
They have been friends through thick and thin.
Они были друзьями в горе и в радости.
Definitions
The phrase 'thick and thin' refers to all kinds of situations, both good and bad, easy and difficult. It is often used in the expression 'through thick and thin,' meaning to support or stay with someone regardless of the circumstances.
Words
thick

adjective
толстый
thin

adjective
тонкий