What is the meaning of blush?

noun

• A rosy color (especially in the cheeks) taken as a sign of good health.
  • synonyms: bloom, flush, rosiness
• Sudden reddening of the face (as from embarrassment or guilt or shame or modesty.
  • synonyms: flush

verb

• Turn red, as if in embarrassment or shame.
  • usage: "The girl blushed when a young man whistled as she walked by"
  • synonyms: crimson, flush, redden
• Become rosy or reddish.
  • usage: "her cheeks blushed in the cold winter air"