failing

Adjective

• below acceptable in performance
  • received failing grades
    

Noun

• failure to reach a minimum required performance
  • his failing the course led to his disqualification
    
  • he got two flunks on his report
    

• a flaw or weak point
  • he was quick to point out his wife's failings
    

Related words

• Synonyms: 
  flunk , weakness
• Antonyms: 
  passing , pass , qualifying