What is the meaning of efflorescence?

noun

• The period of greatest prosperity or productivity.
  • synonyms: flower, prime, peak, heyday, bloom, blossom, flush
• Any red eruption of the skin.
  • synonyms: rash, roseola, skin rash
• The time and process of budding and unfolding of blossoms.
  • synonyms: blossoming, flowering, florescence, inflorescence, anthesis
• A powdery deposit on a surface.
  • synonyms: bloom