The Definition of Marriage is the 15th episode of the eighth season and 185th overall.
The big day has finally arrived as Grace and James get ready for their green-card wedding. To Grace's dismay, Karen takes it upon herself to ignore her wish for a low-key wedding ceremony and decides to arrange a huge affair instead including hiring the legendary Hall & Oates singing duo to perform "Maneater" at the ceremony.
As the ceremony gets underway, Grace begins to feel incredibly sick, but she's confident in her ability to carry on with the marriage. As Grace prepares to walk down the aisle and begins taking her vows, she becomes extremely dizzy and "barfy". She insists she is okay, but Will puts the ceremony on hold in order to have a private talk with Grace. Will asks her again if she is sure she wants to marry James and Grace reassures that she definitely wants to go through with the wedding.
Jack spends the wedding day flirting and "testing" James to make sure he is "good enough" for Will while also being incredibly annoyed with Karen. During the ceremony Jack appears next to James, while he is serenading Will, completely naked for no other reason that testing James.
Post wedding, James and Will are happily enjoying breakfast talking about how, even though it was a weird ceremony, the best part was James singing Stevie Wonder to Will. James admits that he has no recollection of doing any of that given that he took a couple of Karen's pills. The two are interrupted by Jack, who continues to flirt with James, and Karen who mistakes James for Grace. It's then that Grace enters informing everyone that she was not sick, but pregnant.
- Eric McCormack (Will Truman)
- Debra Messing (Grace Adler)
- Sean Hayes (Jack McFarland)
- Megan Mullally (Karen Walker)
- Shelley Morrison (Rosario Salazar)
- Daryl Hall (Himself)
- John Oates (Himself