an unexpected(/undeserved)gain;a thing which comes to hand unexpectedly;a windfall ❍ 他从祖父那里得到一笔数目可观的遗产，但他把这笔遗产看作是～，全都捐献给一所慈善机关了。He received a considerable legacy from his grandfather,but he regarded it as a windfall and donated it all to a charitable institution.