Cipher or Cypher

Brits have a new Royal Cypher in September 2022

Cypher of King Charles III in Scotland

CYPHER or CIPHER? Is there a difference? Yes, one is an heraldic device or monogram and the other is a cryptic message; though the distinction is often a matter of petty pedantry. After the Great War, in 1919, The British Government established GCCS which became GCHQ.

GCCS or Government Code and Cypher School

Someone, somewhere in Whitehall, decided that CYPHER is Greek, but it is as Greek as TYPHOON (meaning NOT). The word came to English from Medieval Italian and meant null or empty or zero: 1350-1400 Middle English siphre; Medieval Latin ciphra; Arabic ṣifr empty, zero; translation of Sanskrit śūnyā empty. In heraldry, it is a device or moniker peculiar to a noble house. More on the word here.

For a more detailed description of Royal Cypher, here is a Wiki page ⨌ to click.