Right-hander Elliot Zoellner pitched 3 1/3 scoreless innings of relief, but the Terps faltered late.
Weather forced Thursday's game to continue on Friday morning.
Right-hander Hunter Parsons allowed just one run in 7 1/3 innings.
Lee started 4-for-27, but is now hitting a team-best .301.
The Terps swept the Hawkeyes to ensure their season continues.
The Terps can clinch a spot in the Big Ten tournament with a win Saturday.
The Terps allowed four runs in the ninth, but AJ Lee's walk-off home run ended it.
The Terps will need to find success against Iowa and get help from around the conference.
The Terps will take on Iowa next in their final Big Ten series of the regular season.
The Terps have dropped five of their last six contests.