noun

• (by extension, collective) A group of such animals, also of locomotives.
  "He had the finest stud in England, and his delight was to win plates from Tories."
• (colloquial) A sexually attractive, promiscuous male.
  "Well, I'll tell you the truth now. I ain't a for-real cowboy, but I am one hell of a stud!"
• (LGBTQ, slang) A sexually dominant lesbian, chiefly African-American.
  "Down and lonely stud, 23 years old, wants comfort from sweet-hearted fem."

noun

• (jewelry) A style of earring where the decorative element is mounted on a straight post.
  "She's wearing studs in her ears."
• (construction) A vertical post, especially one of the small uprights in the framing for lath and plaster partitions, and furring, and upon which the laths are nailed.
• (obsolete) A stem; a trunk.
  "Seest not this same hawthorn stud?"
• (poker) A type of poker in which the player cannot discard, and some of the cards are exposed.
  "At an old saloon on a street of mud / There at a table, dealing stud / Sat the dirty, mangy dog that named me "Sue""