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

(usually of a decision) 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."

Determined by impulse rather than reason; heavy-handed.

Any, out of all that are possible.

"The equation is true for an arbitrary value of x."

Determined by independent arbiter.

Not representative or symbolic; not iconic.