adjective /ˈɑːbɪtrəri,ˈɑːrbɪtrɛri/
a) Based on individual discretion or judgment; not based on any objective distinction, perhaps even made at random.
Benjamin Franklins designation of "positive" and "negative" to different charges was arbitrary. In fact, electrons flow in the opposite direction to conventional current.
The decision to use 18 years as the legal age of adulthood was arbitrary, as both age 17 and 19 were reasonable alternatives.
See Also: arbit, arbiter, arbitrable, arbitrage, arbitrarily, arbitrariness, arbitrary and capricious, arbitrate, arbitration, arbitrator
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