What does dei-gra-reg-fid-def mean?

Answer 1

The legend DEI GRA REG FID DEF is abbreviated Latin and has appeared on British Coins and many coins of the various Commonwealth countries in one form or another for many years.

The phrase "VICTORIA DEI GRA BRITT REGINA FID DEF IND IMP" is mostly abbreviated from Latin. The literal definition is - "Victoria by the Grace of God, Queen of the British territories, Defender of the Faith, Empress of India".

The equivalent phrase for Queen Victoria's successor, King Edward VII, is - "EDWARDVS VII DEI GRA BRITT OMN REX FID DEF IND IMP". The literal definition is - "Edward VII by the Grace of God, King of all the British territories, Defender of the Faith, Emperor of India".

The phrase varies as the Monarch and the gender of the Monarch changes, and as the circumstances of the British Empire/Commonwealth changes.

The expression does not describe the coin, but is part of the many titles of the king or queen, whoever he or she may be at the time.