These words describe things, especially events, that happen by chance and do not follow a plan, or have a reason or cause.
The most common word for this, and the one with the broadest meaning, israndom.Randomcan be used to describe things that happen, are done, or are chosen by chance and without intentionally making it happen.
It was a random encounter between two long-lost friends.
The study was based on a random selection of students in their first two years of university.
My nan always has a random assortment of sweets available.
You can also use the adjectivechanceto describe things that happen in a way that is not planned and does not appear to have a cause or a reason.
A chance meeting brought them back together.