adjective. Not defeatable; impossible to defeat.

noun. Something that has an undefeatable quality.

"Having that kind of undefeatable narrative to work with gave the performers a great deal of freedom for experimentation while remaining clearly comprehensible."

defeatable  undefeatability  undefeatableness  

all-party  andobsessive  anglo-dutch  anti-japanese  arainbow  

undetectable  unrepeatable  

impenetrable  impregnable  invincible  invulnerable