Mila Kunis and Ashton Kutcher Credit: Jeff Kravitz/FilmMagic; Stephen Lovekin/Getty Images

Mila Kunis and Ashton Kutcher don't need to define their relationship.

The Ted actress, 28, and her former That '70s Show costar, 34, looked tight as they zoomed around Hollywood on Kutcher's motorcycle June 17. But as a source recently told Us Weekly, the actors -- who were spotted sharing meals several times during the spring and even took a three-day road trip getaway outside L.A. in late April -- are not an official couple.

"They're not exclusive, but they are hanging out and seeing where it's going," a source close to the pair explained.

Kunis and Kutcher are certainly making up for lost time. Though he was married to Demi Moore, 49, for six years, and she was in a longterm relationship with Macaulay Culkin, 31, "they've been hot for each other for years," a second insider said. "It stretches back to when they were friends on their show!"

Tell Us: Do you think Mila Kunis and Ashton Kutcher are a good match?