Thoroughly reliable; certain not to fail: a copper-bottomed guarantee
[from earlier usage referring to the copper sheathing of the bottom of a ship]
More example sentences
- Mr Brown failed to give a copper-bottomed assurance that Tony Blair would lead the party into the next election, saying only that it was ‘a matter for him’.
- He can keep quiet and hope Tony will repay loyalty on this occasion - but that has not proved a copper-bottomed guarantee on any issue in the past.
- He fuelled concern by stating that he could not offer copper-bottomed guarantees that there would not be further losses.