What is the meaning of stupid?

noun

• A person who is not very bright.
  • usage: "The economy, stupid"
  • synonyms: stupid person, stupe, dullard, dolt, pudding head, pudden-head, poor fish, pillock

adjective

• Lacking or marked by lack of intellectual acuity.
• In a state of mental numbness especially as resulting from shock.
  • usage: "he had a dazed expression on his face"; "lay semiconscious, stunned (or stupefied) by the blow"; "was stupid from fatigue"
  • synonyms: dazed, stunned, stupefied
• Lacking intelligence.
  • usage: "a dull job with lazy and unintelligent co-workers"
  • synonyms: unintelligent