dawn on or dawn upon. = To become evident or understood. Dawn (up) on someone. (Upon is formal) Past tense: dawned; past participle: dawned Flash across your mind. Come to mind. Occur to me. Become apparent to someone; [for something] to be suddenly realised by someone. Come into your head. To begin to be perceived, or understood by someone. dawned upon. Become evident. Strike. I get it. Register. To finally understand. See the light.