Other forms: transepts
A transept is the arm that crosses the nave of a church. The north transept, cross the transept, a transept window.
The two together make the building a cross when seen from above, which is the whole point of the plan. The crossing is where they meet, and the tower usually sits above it.
1nountranseptThe arm that crosses the nave of a church.
“The choir sang from the north transept of the cathedral.”
transept is a part.
New Latin transeptum is trans, across, plus saeptum, an enclosure.
Latin
trans- — across
New Latin
transeptum
French
transept
English, today
transept
Built from
From French transept, from New Latin transeptum, from Latin trans- (“across”) + saeptum (“fence, partition, enclosure”).
Etymology from Wiktionary, CC BY-SA