Plainly
look up a word, understand it — no rabbit hole
arbitrary
adjectiveAR-bih-truh-ree
meaning in plain English
Decided without a clear reason or plan, just picked on a whim.
Think arbitrary = random pick — like rolling dice to choose an arbitrary winner.
for example
The rule against blue pens felt arbitrary because no one could explain why it existed.
If something is arbitrary, there is no real reason behind it. Why does the club meet at 7:13 instead of 7:30? Because someone picked an arbitrary time and everyone just went along with it.