insubstantial

Adjective

• lacking in nutritive value
  • the jejune diets of the very poor
    

• lacking material form or substance; unreal
  • as insubstantial as a dream
    
  • an insubstantial mirage on the horizon
    

Related words

• Synonyms: 
  jejune , unsubstantial , unreal
• Antonyms: 
  substantial , real , material