noun

• (diminutive, especially with a possessive) A son of any age.
  "Low as that tide has ebbed with me, / It still reflects to memory’s eye / The hour, my brave, my only boy, / Fell by the side of great Dundee."
• (endearing, diminutive) A male human younger than the speaker.
• (informal, sometimes mildly derogatory) A male human of any age, as opposed to a "girl" (female human of any age).
  "boys' club"
• (obsolete) A male of low station, (especially as pejorative) a worthless male, a wretch; a mean and dishonest male, a knave.
  "Do’ſt thou call mee foole boy?"

verb

• (transitive) To act as a boy (in allusion to the former practice of boys acting women's parts on the stage).
  "I shall see some squeaking Cleopatra boy my greatness."

adj

• (education) Initialism of beginning of year.
  "Coordinate term: EOY"