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