1. Fig. [for a fact] to become apparent to someone; [for something] to be suddenly realized by someone

1. It suddenly dawned on me that I hadn't eaten all day.

2. On the way home, it dawned on me that I had never returned your call, so when I got home I called immediately.

3. The solution finally dawned on him.

4. It began to dawn on her that she was lost.

5. It finally dawned on him that she’d been joking.

6. I was about to pay for the shopping when it suddenly dawned on me that I'd left my wallet at home.