Fig. a bit of luck; a lucky happening. I had a stroke of luck and found Tom at home when I called. He's not usually there. Unless I have a stroke of luck, I'm not going to finish this report by tomorrow.
something good that happens to you by chance Phil was driving up to Manchester that evening and gave me a lift so that was a stroke of luck.By a stroke of luck, someone at work happened to be selling very cheaply exactly the piece of equipment that I needed.