What does the word instant mean?

Usage examples for instant

  1. He was up in an instant. – The Puppet Crown by Harold MacGrath
  2. He saw in an instant something was wrong. – The Adventures of a Three-Guinea Watch by Talbot Baines Reed
  3. Imagine yourself for an instant to be Bramleigh, and what you would have said to this? – The Bramleighs Of Bishop's Folly by Charles James Lever