" unresistant "

1: lacking protection from danger or resistance against attack;

  * e.g., " ... a weakened immune system that rendered him unresistant to pneumonia "

•  Synonyms : 

•  defenseless,

•  exposed,

•  helpless,

•  susceptible,

•  undefended,

•  unguarded,

•  unprotected,

•  vulnerable

•  Antonyms : 

•  guarded,

•  invulnerable,

•  protected,

•  resistant,

•  shielded

2: receiving or enduring without offering resistance;

  * e.g., " ... the kitten was surprisingly unresistant when the vet examined her "

•  Synonyms : 

•  acquiescent,

•  nonresistant,

•  passive,

•  resigned,

•  tolerant,

•  tolerating,

•  yielding

•  Antonyms : 

•  protesting,

•  resistant,

•  resisting,

•  unyielding