Antonyms for Efficient

Antonyms starting with letter I

• inefficient

  effective, competent, adept
• incompetent

  competent, adept
• ineffective

  adept, inefficient
• ineffectual

  effective, inefficient
• impotent

  adept
• idle

  adept
• incapable
• inept

  competent
• inactive
• inadequate
• inoperative
• inexperienced
• inexpert