What is the meaning of keen?

noun

• A funeral lament sung with loud wailing.

verb

• Express grief verbally.
  • usage: "we lamented the death of the child"
  • synonyms: lament

adjective

• Having or demonstrating ability to recognize or draw fine distinctions.
  • usage: "an acute observer of politics and politicians"; "incisive comments"; "icy knifelike reasoning"; "as sharp and incisive as the stroke of a fang"; "penetrating insight"; "frequent penetrative observations"
  • synonyms: acute, discriminating, incisive, knifelike, penetrating, penetrative, piercing, sharp
• Intense or sharp.
  • usage: "suffered exquisite pain"; "felt exquisite pleasure"
  • synonyms: exquisite
• Very good.
  • usage: "he did a bully job"; "a neat sports car"; "had a great time at the party"; "you look simply smashing"
  • synonyms: bang-up, bully, corking, cracking, dandy, great, groovy, neat, nifty, not bad, peachy, slap-up, swell, smashing
• Painful as if caused by a sharp instrument.
  • usage: "a cutting wind"; "keen winds"; "knifelike cold"; "piercing knifelike pains"; "piercing cold"; "piercing criticism"; "a stabbing pain"; "lancinating pain"
  • synonyms: cutting, knifelike, piercing, stabbing, lancinate, lancinating
• Having a sharp cutting edge or point.
  • usage: "a keen blade"