What is the meaning of pinpoint?

noun

• A very brief moment.
  • usage: "they were strangers sharing a pinpoint of time together"
• A very small spot.
  • usage: "the plane was just a speck in the sky"
  • synonyms: speck
• The sharp point of a pin.

verb

• Locate exactly.
  • usage: "can you pinpoint the position of the enemy"; "The chemists could not nail the identity of the chromosome"
  • synonyms: nail