We don't have synonyms for glos'ter yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are glister, gloster and gloser.
(n) :
(obsolete) Abbreviation of Gloucester. [A cathedral city and local government district of Gloucestershire, England, on the river Severn, near the border with Wales.]
(n) :
(obsolete) Abbreviation of Gloucester. [A cathedral city and local government district of Gloucestershire, England, on the river Severn, near the border with Wales.]