Collocations for coincidence - noun

complete, pure, sheer
It was pure coincidence that they were both in Vegas on the same day.

mere
happy, lucky
What a happy coincidence to meet you at the airport just when I wanted to see you.

unfortunate
amazing, bizarre, curious, extraordinary, funny, incredible, odd, remarkable, strange, weird, wonderful

series, set, string
They met through a series of strange coincidences.

happen
Remarkable coincidences do happen in real life.

by (a) coincidence
By coincidence, we both went to the same school.
By an unfortunate coincidence, their house was broken into on the day he lost his job.