transept
noun
tran·sept ˈtran(t)-ˌsept 
: the part of a cruciform church that crosses at right angles to the greatest length between the nave and the apse or choir
also : either of the projecting ends of a transept
transeptal
tran(t)-ˈsep-tᵊl
adjective 
Example Sentences
Recent Examples on the Web Perpendicular to this, one level above, runs an east-west passage that contains a chapel space and an outdoor terrace, placed on axis with the transept of the synagogue. 
Michael J. Lewis, WSJ, 24 Mar. 2022 There are three main piles of debris—in the nave, the crossing and the north transept—as well as material still on top of the remaining vaults. Philip Ball, Scientific American, 9 Jan. 2020 The two western towers were finished and a spire was added to the crossing of the nave and transept. Washington Post, 16 Jan. 2020 The best place from which to see them is the juncture of nave and transept. Bruce Dale, National Geographic, 17 Apr. 2019 In its news release Friday, the Land office noted that in 1995, human remains were were found in the main portion of the church, along the south transept and inside the Monks Burial room in 1989. John C Moritz Austin Bureau Usa Today Network, USA TODAY, 13 Dec. 2019 In 2007, the artist designed a monumental window for the south transept of Cologne Cathedral. Meilan Solly, Smithsonian, 23 Aug. 2019 This was considered such a success that it was repeated some 15 years later on the south transept. Klara Glowczewska, Town & Country, 19 Apr. 2019 Work began on the transept facades, which were completed by his successor, Pierre de Montreuil. National Geographic, 15 Apr. 2019 See More
Michael J. Lewis, WSJ, 24 Mar. 2022 There are three main piles of debris—in the nave, the crossing and the north transept—as well as material still on top of the remaining vaults. Philip Ball, Scientific American, 9 Jan. 2020 The two western towers were finished and a spire was added to the crossing of the nave and transept. Washington Post, 16 Jan. 2020 The best place from which to see them is the juncture of nave and transept. Bruce Dale, National Geographic, 17 Apr. 2019 In its news release Friday, the Land office noted that in 1995, human remains were were found in the main portion of the church, along the south transept and inside the Monks Burial room in 1989. John C Moritz Austin Bureau Usa Today Network, USA TODAY, 13 Dec. 2019 In 2007, the artist designed a monumental window for the south transept of Cologne Cathedral. Meilan Solly, Smithsonian, 23 Aug. 2019 This was considered such a success that it was repeated some 15 years later on the south transept. Klara Glowczewska, Town & Country, 19 Apr. 2019 Work began on the transept facades, which were completed by his successor, Pierre de Montreuil. National Geographic, 15 Apr. 2019 See More Word History
Etymology
New Latin transeptum, from Latin trans- + septum, saeptum enclosure, wall
First Known Use
circa 1542, in the meaning defined above