An occurrence by chance or coincidence; something that happens accidentally rather than by necessity (used as a noun or na-adjective).
彼らは偶然の一致で同じ日に同じ店にいた。
By coincidence they were at the same shop on the same day.
偶然の出会いが人生を変えることもある。
A chance encounter can sometimes change a life.
それは偶然の一致だと私は思う。
I think that's a mere coincidence.
An adverb meaning 'by chance' or 'unexpectedly' — indicating something happened without planning or intention.
昨日、偶然昔の友達に駅で会った。
Yesterday I unexpectedly ran into an old friend at the station.
その知らせを偶然聞いて驚いた。
I was surprised to hear the news by chance.
彼は偶然にもその賞を受賞した。
He won that prize by chance.
In philosophy, 'contingency' or chance — the concept contrasted with necessity, referring to events not strictly determined by prior causes.
哲学の講義で偶然と必然の区別について議論した。
In the philosophy lecture we discussed the distinction between contingency and necessity.