noun

• (equestrianism) A horse trained for steeplechasing; a steeplechaser.
  ""[I]t looked like The Fellow was the best steeplechaser in many years. He'd earned the best speed rating I'd ever given a chaser.""
• (equestrianism, obsolete) A hunter (a horse bred and trained for use in hunting).
• (slang) A drink consumed after another of a different kind.
  "beer chaser"
• (timber industry, obsolete) Someone who follows logs out of the forest in order to signal a yarder engineer to stop them if they become fouled
  "...on one end known as a Bardon choker hook, to facilitate making a loop. It stays tight and makes it unnecessary for the "chaser" or "choker setter" to follow the "turn" to the landing as might have to be done if tongs are used"

noun

• (nautical) A chase gun.
  "bow chaser; stern chaser"