Unexpectedly; surprisingly — used when something happens that was not anticipated.
駅で思いがけず旧友に会った。
I unexpectedly met an old friend at the station.
思いがけず仕事が早く終わったので映画に行った。
Work finished earlier than expected, so I went to the movies.
彼から思いがけずプレゼントをもらって驚いた。
I was surprised to receive an unexpected gift from him.
思いがけず良い結果が出た。
An unexpectedly good result came out.