arbitrary

adj

1. (usually)Based on individual discretion or judgment; not based on any objective distinction, perhaps even made at random.

   “Benjamin Franklin's designation of "positive" and "negative" to different charges was arbitrary.”

   “The decision to use 18 years as the legal age of adulthood was arbitrary, as both age 17 and 19 were reasonable alternatives.”

2. Determined by impulse rather than reason; often connoting heavy-handedness.

   “1937/1938, Albert Einstein, letter to Max Born The Russian trials were Stalin's purges, with which he attempted to consolidate his power. Like most people in the West, I believed these show trials to be the arbitrary acts of a cruel dictator.”

   “The bromide conforms to everything sanctioned by the majority, and may be depended upon to be trite, banal, and arbitrary.”

3. Any, out of all that are possible.

   “The equation is true for an arbitrary value of x.”

4. Determined by independent arbiter.
5. Not representative or symbolic; not iconic.

noun

1. Anything arbitrary, such as an arithmetical value or a fee.

   “And in this long chain of consistence, a chain stretching from the long dead to the far unborn, the notion of the arbitrary could only survive as the notion of a pre-established arbitrary.”