adj

• (of a gas) Thin; of low density.
• (UK, slang) Good; enjoyable.
  "Sees her reflection in a butcher shop. She finds it all quite rare That her meat's all vanity fair."

noun

• (gaming) A scarce or uncommon item.
  "Most of the time, you do this by trading low-valued rares for more valuable ones or trading uncommons for rares. Other times it's trading cards that are in print for ones that are out of print, or low-value rares for good uncommons."

adj

• (cooking) Particularly of meat, especially beefsteak: cooked very lightly, so the meat is still red.
  "Then Curds and Cream, the Flow'r of Country Fare, / And new-laid Eggs, which Baucis’ buſie Care / Turn’d by a gentle Fire, and roaſted rare."

verb

• (US, intransitive) To rear, rise up, start backwards.
  "Frank pretended to rare back as if bedazzled, shielding his eyes with a forearm."
• (US, transitive) To rear, bring up, raise.
  "Here I have to say that I was walking along dark-hearted, my nose out of joint about Audie's notice of her, for just as quickly as my feelings kindled, my old envy rared."