inevitable

Synonyms: all locked up assured binding compulsory decided decreed destined determined doomed fated fateful fixed for certain foreordained imminent impending ineluctable ineludible inescapable inexorable inflexible in the bag irresistible irrevocable necessary no ifs ands or buts obligatory ordained pat prescribed settled sure unalterable unavoidable undeniable unpreventable without recourse

Antonyms: avoidable doubtful escapable fortuitous preventable uncertain unlikely unsure