We don't have synonyms for king-of-arms yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are kings-of-arms, king-at-arms and king of arms.
(n) :
One of the three chief heralds of the College of Arms, designated as Garter (Principal King of Arms), Clarenceux (for England south of the Trent and Wales), and Norroy & Ulster (for England north of the Trent and Northern Ireland).
(n) :
One of the three chief heralds of the College of Arms, designated as Garter (Principal King of Arms), Clarenceux (for England south of the Trent and Wales), and Norroy & Ulster (for England north of the Trent and Northern Ireland).