Other forms: transepts
A transept is the section of a building that runs perpendicular to its main part, forming a kind of cross shape. Many transepts are found in churches.
If you can remember that trans, "across" in Latin, sometimes conveys the idea of "cross," you've nailed this one: it's the cross part in a cross-shaped church, the other section being the "nave." The Latin word saeptum forms the end of transept. It means "fence or enclosure." You're most likely to come across a transept in a Romanesque or Gothic church, although it can also mean a hall or wing that crosses the main part of a building.