What is the meaning of ebb?

noun

• A gradual decline (in size or strength or power or number.
  • synonyms: ebbing, wane
• The outward flow of the tide.
  • synonyms: reflux

verb

• Flow back or recede.
  • usage: "the tides ebbed at noon"
  • synonyms: ebb away, ebb down, ebb out, ebb off
• Hem in fish with stakes and nets so as to prevent them from going back into the sea with the ebb.
• Fall away or decline.
  • usage: "The patient's strength ebbed away"