arbitrary · adjective /ˈɑr.bɪ.trer.i/
arbitrary
C2 not based on a system or principles and often seeming unfair
Dictionary example:
an arbitrary decision
Learner example:
To start with, this arbitrary act is, as far as I am concerned, one of the worst aggressions to nature, as an area of about two miles of gre[e]n[e]ry will have to be completely destroyed to give [a] place to an absurd parking garage. (Certificate of Proficiency in English; C2; Portuguese)
