noun

• (colloquial) A very short, unspecified length of time.
  "I’ll be back in a jiffy."
• (computing) A unit of time defined by the frequency of its basic timer – historically, and by convention, 0.01 of a second, but some computer operating systems use other values.
  "The FOR...NEXT loop for TIME increments by STEP 2 (every two jiffies) for two reasons: 1) the printing of 60 jiffies a second is too fast to read, and 2) the printing of each jiffy takes longer than its incrementations; this would delay the loop, so the printing of TIME$ is slower than it should be."
• (electronics) The length of an alternating current power cycle (1/60 or 1/50 of a second).
• (physics) The time taken for light to travel a specified distance in a vacuum, usually one centimetre (approximately 33.3564 picoseconds), but sometimes one foot or the width of a nucleon.