rock solid

comparative more rock solid · superlative most rock solid

1. Physically very solid; very difficult to move.

   Synonyms: rock hard, solid as a rock

2. figurativelyVery strong and dependable.

   Wolfgang Schäuble said on Tuesday he had “no concerns” about Deutsche Bank, speaking shortly after John Cryan, who was appointed to run Germany’s biggest bank seven months ago, sent an email to his 100,000 staff to assure them the bank was “absolutely rock solid”.

   2016 February 9, Jill Treanor, quoting John Cryan, “Deutsche boss tells staff the bank is ‘rock solid’ as shares slide”, in The Guardian