What is the meaning of lacking?

verb

• Be without.
  • usage: "This soup lacks salt"; "There is something missing in my jewelry box"
  • synonyms: miss, lack

adjective

• Inadequate in amount or degree.
  • usage: "a deficient education"; "deficient in common sense"; "lacking in stamina"; "tested and found wanting"
  • synonyms: deficient, wanting
• Nonexistent.
  • usage: "the thumb is absent"; "her appetite was lacking"
  • synonyms: absent, missing, wanting