unassailably
1. [ adverb ] in an unalterable and unchangeable manner
Synonyms: unchangeably immutably unalterably
Examples:

"his views were unchangeably fixed"

Related terms: unchangeable unalterable ironclad immutable immutable ironclad
Similar spelling:   unassailable
  unscalable
  unsalable
  unusually
  unsyllabic
  unskillful
  unsyllabled