What is the meaning of avail?

noun

• A means of serving.
  • usage: "of no avail"; "there's no help for it"
  • synonyms: help, service

verb

• Use to one's advantage.
  • usage: "He availed himself of the available resources"
• Be of use to, be useful to.
  • usage: "It will avail them to dispose of their booty"
• Take or use.
  • usage: "She helped herself to some of the office supplies"
  • synonyms: help